## Chapter 15 – Probability Exercise Ex. 15A

Fill in the blanks:

(i) The

probability of an impossible event is ……. .

(ii) The

probability of a sure event is ……. .

(iii) For

any event E, P(E) + P(not E)= …… .

(iv) The

probability of a possible but not a sure event lies between …… and ……. .

(v) The

sum of probabilities of all the outcomes of an experiment is …….. .

(i) The probability of an

impossible event is ** zero**.

(ii) The probability of a sure event is ** one**.

(iii) For any event E, P(E) +

P(not E)= ** one** .

(iv) The probability of a possible but not a sure event

lies between ** zero** and

**.**

__one__(v) The sum of probabilities of all the outcomes of an

experiment is ** one**.

A coin is tossed once. What is the

probability of getting a tail?

Two

coins are tossed simultaneously. Find the probability of getting

(i) exactly

1 head

(ii) at

most 1 head

(iii) at

least 1 head

A die is thrown once. Find the probability of getting:

(i)An even number

(ii)A number less than 5

(iii)A number greater than 2

(iv)A number between 3 and 6

(v)A number other than 3

(vi)The number 5

In a throw of a dice, all possible outcomes are 1, 2, 3, 4, 5, 6

Total number of possible outcomes = 6

(i)Let E be event of getting even number

Then, the favorable outcomes are 2, 4, 6

Number of favorable outcomes= 3

P(getting a even number)= P(E) =

(ii)Let R be the number less than 5

Then, the favorable outcomes are 1, 2, 3, 4

Number of favorable outcomes = 4

P(getting a number less than 5)= P(R) =

(iii)Let M be the event of getting a number greater than 2

Then, the favorable outcomes are 3, 4, 5, 6

Number of favorableoutcomes = 4

P(getting a number greater than 2)= P(M)

(iv)Let N be the number lying between 3 and 6

Then the favorable outcomes are 4, 5

Number of favorable outcomes = 2

P(getting a number 3 and 6)= P(N) =

(v)Let G be event of getting a number other than 3

Then the favorable outcomes are 1, 2, 4, 5, 6

Number of favorable outcomes = 5

P(getting a number other than 5)=P(G) =

(vi)Let T be event of getting a number 5

Then the favorable outcome is 5

Number of favorable outcomes = 1

P(getting a number 5)=P(T)

A letter of English alphabet is chosen at

random. Determine the probability that the chosen letter is a consonant.

It is known that a box of 200 electric bulbs contains 16 defective bulbs. One bulb is taken out at random from the box. What is the probability that the bulb drawn is

(i)Defective

(ii)Non – defective?

Total number of bulbs = 200

Number of defective bulbs = 16

(i)Let be the event of getting a defective bulb

Total number of defective bulbs = 16

P(getting defective bulbs) = P() =

(ii)Let be the event of “getting non – defective bulb”

P(getting non defective bulb) =

If

the probability of winning a game is 0.7, what is the probability of losing

it?

There are 35 students in a class of whom 20 are boys

and 15 are girls. From these students one is chosen at random. What is the

probability that the chosen student is a (i) boy,

(ii) girl?

In a lottery there are 10 prizes and 25

blanks. What is the probability of getting a prize?

250 lottery tickets were sold and there are 5 prizes on these tickets. If Kunal has purchased one lottery ticket, what is the probability that he wins a prize?

Total number of tickets sold = 250

Number of prizes = 5

Let E be the event getting a prize

Number of favorable outcomes = 5

P(getting a prize) =

17 cards numbered 1, 2, 3, 4, ….., 17 are put in a box and mixed thoroughly. A card is

drawn at random from the box. Find the probability that the card drawn bears

(i) an odd number (ii) a number divisible by 5.

A game of chance consists of spinning an

arrow, which comes to rest pointing at one of the numbers 1, 2, 3, 4, 5, 6,

7, 8 and these are equally likely outcomes. Find the probability that the

arrow will point at any factor of 8.

In a family of 3 children, find the

probability of having at least one boy.

A bag contains 4 white balls, 5 red balls,

2 blacks balls and 4 green balls. A ball is drawn at

random from the bag. Find the probability that it is (i)

black, (ii) not green, (iii) red or white, (iv)

neither red nor green.

A card is drawn at random from a well shuffled pack of 52 cards. Find the probability that the card drawn is neither a red card nor a queen.

There are 26 red cards containing a 2 queensand 2 more black queens are there in a pack of cards

P(getting a red card or a queen)

P(getting neither a red card nor a queen) =

A card is drawn at random from a

well-shuffled pack of 52 cards. Find the probability of getting (i) a red king, (ii) a queen or a jack.

A card is drawn from a well-shuffled pack

of 52 cards. Find the probability of getting (i) a

red face card (ii) a black king.

Two different dice are tossed together. Find

the probability that (i) the number on each dice is

even, (ii) the sum of the numbers appearing on the two dice is 5.

Two different dice are rolled

simultaneously. Find the probability that the sum of numbers in the two dice

is 10.

When two dice are tossed together, find the

probability that the sum of numbers on their tops is less than 7.

Two dice are rolled together. Find the

probability of getting such numbers on two dice whose product is a perfect

square.

Two dice are rolled together. Find the

probability of getting such numbers on the two dice whose product is 12.

Cards marked with numbers 5 to 50 are

placed in a box and mixed thoroughly. A card is drawn from the box at random.

Find the probability that the number on the number on the taken out card is (i) a prime number less than 10 (ii) a number which is a

perfect square.

A game of chance consists of spinning an arrow which is equally likely to come to rest pointing to one of the numbers 1, 2, 3,…. , 12 as shown in the figure. What is the probability that it will point to

(i)6?

(ii)An even number?

(iii)A prime number?

(iv)A number which is a multiple of 5?

Spinning arrow may come to rest at one of the 12 numbers

total number of outcomes = 12

(i)Probability that it will point at 6 =

(ii)Even numbers are 2, 4, 6, 8, 10 and 12. There are 6 numbers.

Probability that it points at even numbers =

(iii)The prime numbers are 2,3 5, 7 and 11. There are 5 prime numbers.

Probability that it points at prime number =

(iv)There are 2 numbers divisible by 5. These are 5 and 10.

Probability that a number is a multiple of 5 =

12 defective pens are accidently mixed with

132 good ones. It is not possible to just look at pen and tell whether or not

it is defective. One pen is taken out is good one.

A lot consists of 144 ballpoint pens of

which 20 are defective and others good. Tanvy will

buy a pen if it is good, but will not buy it if it is defective. The

shopkeeper draws one pen at random and gives it to her. What is the probability

that (i) she will buy it, (ii) she will not buy it?

A box contains 90 discs which are numbered

from 1 to 90. If one disc is drawn at random from the box, find the

probability that it bears (i) a two-digit number,

(ii) a perfect square number, (iii) a number divisible by 5.

(i) A lot of 20 bulbs contain 4 defective ones.

One bulb is drawn at random from the lot. What is the probability that this

bulb is defective?

(ii) Suppose the bulb drawn in (i) is not defective and not replaced. Now, bulb is drawn

at random from the rest. What is the probability that this bulb is not

defective?

A bag contains lemon-flavoured

candies only. Hema takes out one candy without

looking into the bag. What is the probability that she takes out (i) an orange-flavoured candy?

(ii) a lemon-flavoured

candy?

There are 40 students in a class of whom 25

are girls and 15 are boys. The class teacher has to select one student as a

class representative. He writes the name of each student on a separate card,

the cards being identical. Then the puts cards in a bag and stirs them

thoroughly. She then draws one card from the bag. What is the probability

that the name written on the card is the name of (i)

a girl? (ii) a boy?

One card is drawn from a well-shuffled deck of 52 cards. Find the probability of drawing

(i)An ace

(ii)A ‘4’ of spades

(iii)A ‘9’ of a black suit

(iv)A red king

Total number of all possible outcomes = 52

(i)P(getting an ace) =

(ii)P(getting a ‘4’ of spades) =

(iii)P(a ‘9’ of a black suit) =

(iv)P(getting a red king) =

A card is drawn at random from a well- shuffled deck of 52 cards. Find the probability of getting

(i)A queen

(ii)A diamond

(iii)A king or an ace

(iv)A red ace

Total numbers of cards = 52

(i)There are 4 queen cards in a pack of cards

Probability of getting a queen card =

(ii)There are 13 cards of diamond in a pack of cards

probability ofgetting a diamond card =

(iii)In a pack of cards there are 4 kings and 4 aces

Number of such cards = 4 + 4 = 8

Probability of getting either a king or an ace =

(iv)There are two red aces in a pack of cards

probability of getting a red ace =

One card is drawn from a well-shuffled deck

of 52 cards. Find the probability of getting

(i) a king of red suit

(ii) a face card

(iii) a red face card

(iv) a queen of black suit

(v) a jack of hearts

(vi) a spade

A card is drawn at random from a well-shuffled deck of playing cards. Find the probability that the card drawn is

(i)A card of spades or an ace

(ii)A red king

(iii)Either a king or a queen

(iv)Neither a king nor a queen

Total number of cards = 52

(i)There are 13 cards of spade (including 1 ace) and 3 more ace cards are there in a pack of cards

P(getting a card of spades or an ace) =

(ii)There are 2 red kings in a pack of cards

P(getting a red king) =

(iii)There are 4 kings and 4 queens in a pack of cards

P(getting either a king or a queen) =

(iv)P(getting neither a king nor a queen) =

## Chapter 15 – Probability Exercise Ex. 15B

A box contains 25 cards numbered from 1 to

25. A card is drawn at random from the bag. Find the probability that the

number on the drawn card is (i) divisible by 2 or

3, (ii) a prime number.

A box contains cards numbered 3, 5, 7, 9, …., 35, 37. A card is drawn at random from the box. Find

the probability that the number on the card is a prime number.

Cards numbered 1 to 30 are put in a bag. A card is

drawn at random from the bag. Find the probability that the number on the

drawn card is (i) not divisible by 3, (ii) a prime

number greater that 7, (iii) not a perfect square

number.

Cards bearing numbers 1, 3, 5, …., 35 are kept in a bag. A card is drawn at random from

the bag. Find the probability of getting a card bearing (i)

a prime number less than 15, (ii) a number divisible by 3 and 5.

A box contains cards bearing numbers 6 to

70. If one card is drawn at random from the box, Find the probability that it

bears (i) a one-digit number, (ii) a number

divisible by 5, (iii) an odd number less than 30, (iv) a composite number

between 50 and 70.

Cards marked with numbers 1, 3, 5, ……, 101 are placed in a bag and mixed thoroughly. A card

is drawn at random from the bag. Find the probability that the number on the

drawn card is (i) less than 19, (ii) a prime number

less than 20.

Tickets numbered 2, 3, 4, 5,.. , 100, 101 are placed in a box and mixed thoroughly. One ticket is drawn at random from the box. Find the probability that the number on the ticket is

(i)An even number

(ii)A number less than 16

(iii)A number which is a perfect square

(iv)A prime number less than 40

Total number of tickets = 100

(i)Even numbers are 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100

Total number of even number = 50

P(getting a even number) =

(ii)Numbers less than 16 are 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15

Total number of numbers less than 16 is 14

P(getting a number less than 16) =

(iii)Numbers which are perfect square are 4, 9, 16, 25, 36, 49, 64, 81, 100

Total number of perfect squares = 9

P(getting a perfect square) =

(iv)Prime numbers less than 40 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37

Total number of prime numbers =12

P(getting a prime number less 40) =

A

box contains 80 discs, which are numbered from 1 to 80. If one disc is drawn

at random from the box, find the probability that it bears a perfect square

number.

A piggy bank contains

hundred 50-p coins, seventy Rs. 1 coin, fifty Rs. 2 coins and thirty Rs. 5

coins. If it equally likely that one of the coins will fall out when the bank

is turned upside down, what is the probability that the coin (i) will be a Rs. 1 coin? (ii) will

not be a Rs. 5 coins (iii) will be 50-p or a Rs. 2 coin?

A carton consists of 100 shirts of which 88

are good and 8 have minor defects. Rohit, a trader,

will only accept the shirts which are good. But, Kamal,

another trader, will only reject the shirts which have major defect. One

shirt is drawn at random from the carton. What is the probability that it is

acceptable to (i) Rohit,

(ii) Kamal?

A group consists of 12 persons, of which 3

are extremely patient, other 6 are extremely honest and rest are extremely

kind. A person from the group is selected at random. Assuming that each

person is equally likely to be selected, find the probability of selecting a

person who is (i) extremely patient, (ii) extremely

kind or honest. Which of the above values you prefer more?

Two dice are thrown simultaneously. What is the probability that

(i)5 will not come up on either of them

(ii)5 will not come up on at least one,

(iii)5 will come up at both the dice

Two dice are thrown simultaneously

Total number of outcomes = 6 6 = 36

(i)Favourable cases are: (1, 1), (1, 2), (1, 3), (1, 4), (1, 6), (2, 1), (2, 2), (2, 3), (2, 4), (2, 6), (3, 1), (3, 2), (3, 3), (3, 4), (3, 6), (4, 1), (4, 2), (4, 3), (4, 4), (4, 6), (6, 1), (6, 2), (6, 3), (6, 4), (6, 6) = 25.

Probability that 5 will not come upon either die

(ii)Favourable cases are: (1, 5), (2, 5), (3, 5), (4, 5), (5, 5), (6, 5), (5, 1), (5, 2), (5, 3), (5, 4), (5, 6) = 11

Probability that 5 will come at least once

(iii)5 will come up on both dice in 1 case = (5,5)

probability that 5 will come on both dice =

Two dice are rolled once. Find the

probability of getting such numbers on two dice whose product is a perfect

square.

A letter is chosen at random from the

letters of the word ‘ASSOCIATION’. Find the probability that the chosen

letter is a (i) vowel (ii) consonant (iii) an S.

Five cards-the ten, jack, queen, king and

ace of diamonds are well shuffled with their faces downwards. One card is

then picked up at random. (a) What is the probability that the drawn card is

the queen?

(b) If the queen is drawn and put aside and

a second card is drawn, find the probability that the second card is (i) an ace, (ii) a queen.

A card is drawn at random from a well

shuffled pack of 52 cards. Find the probability that the card drawn is

neither a red card nor a queen?

What is the probability that an ordinary

year has 53 Mondays?

All red face cards are removed from a pack

of playing cards. The remaining cards are well shuffled and then a card is

drawn at random from them. Find the probability that the drawn card is (i) a red card, (ii) a face card, (iii) a card of clubs.

All kings, queens and aces are removed from

a pack of 52 cards. The remaining cards are well-shuffled and then a card is

drawn from it. Find the probability that the draw card is (i) a black face card, (ii) a red car

A game consists of tossing a one-rupee coin

three times and noting its outcome each time. Find the probability of getting

(i) three heads, (ii) at least 2 tails.

Find the probability that a leap year selected at

random will contain 53 Sundays.

## Chapter 15 – Probability Exercise MCQ

If P(E) denotes the probability of an event E then

(a) P(E)< 0

(b) P(E) > 1

(c) 0 ≤ P(E) ≤1

(d) -1≤ P(E) ≤ 1

If the probability of occurrence of an event is p then the probability of non-happening of this event is

What is the probability of an impossible event?

What is the probability of a sure event?

Which of the following cannot be the probability of an event?

A number is selected at random from the numbers 1 to 30. What is the probability that the selected number is a prime number?

The probability that a number selected at random from the numbers 1,2,3,….15 is a multiple of 4, is

A box contains cards numbered 6 to 50.A card is drawn at random from the box. The probability that draw card has a number which is a perfect square is

A box contains 90 discs, numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears prime number less than 23 is

Cards bearing numbers 2, 3, 4…, 11 are kept in a bag. A card is drawn at random from the bag. The probability of getting a card with a prime number is

One ticket is drawn at random from a bag containing tickets numbered 1 to 40. The probability that the selected ticket has a number, which is a multiple of 7, is

Which of the following cannot be the probability of an event?

If the probability of winning a game is 0.4 then the probability of losing it, is

If an event cannot occur then its probability is

There are 20 tickets numbered as 1, 2, 3…., 20 respectively. One ticket is drawn at random. What is the probability that the number on the ticket drawn is a multiple of 5?

There are 25 tickets numbered as 1, 2, 3, 4…., 25 respectively. One ticket is drawn at random. What is the probability that the number on the ticket drawn is a multiple of 3 or 5?

Card, each market with one of the numbers 6, 7, 8, …, 15, are placed in a box and mixed thoroughly. One card is drawn at random from the box. What is the probability of getting a card with number less than 10?

A die is thrown once. The probability of getting an even number is

The probability of throwing a number greater than 2 with a fair die is

A die is thrown once. The probability of getting an odd number greater than 3 is

A die is thrown once. The probability of getting a prime number is

Two dice are thrown together. The probability of getting the same number on both dice is

The probability of getting 2 heads, when two coins are tossed, is

Two dice are thrown together. The probability of getting a doublet is

Two coins are tossed simultaneously. What is the probability of getting at most one head?

Three coins are tossed simultaneously. What is the probability of getting exactly two heads?

In a lottery, there are 8 prizes and 16 blanks. What is the probability of getting a prize?

In a lottery, there are 6 prizes and 24 blacks. What is the probability of not getting a prize?

A box contains 3 blue, 2 white and 4 red marbles. If a marble is drawn at random from the box, what is the probability that it will not be a white marble?

A bag contains 4 red and 6 black balls. A ball is taken out of the bag at random. What is the probability of getting a black ball?

A bag contains 8 red, 2 black and 5 white balls. One ball is drawn at random. What is the probability that the ball drawn is not black?

A bag contains 3 white, 4 red and 5 black balls. One ball is drawn at random. What is the probability that the ball drawn is neither black nor white?

A card is drawn at random from a well-shuffled deck of 52 cards. What is the probability of getting a black king?

From a well-shuffled deck of 52 cards, one card is drawn at random. What is the probability of getting a queen?

One card is drawn at random from a well-shuffled deck of 52 cards. What is the probability of getting a face card?

One card is drawn at random from a well-shuffled deck of 52 cards. What is the probability of getting a black face card?

One card is drawn at random from a well-shuffled deck of 52 cards. What is the probability of getting a 6?