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Blackberry publication class 8 maths chapter comparing quantities exercise 9B

Exercise 9(A)   Exercise 9(B)   Exercise 9(C)   Exercise 9(D)

EXERCISE 9(B)


Question 1 

Find the S.P. when M.P. =₹ 990 and discount = 10%.

Sol :

We know that

Selling Price = Market Price – Discount

S.P = ( 990 ) – (10% of 990 )

S.P = 990 – 990\times \dfrac{10}{100}

S.P = 990 – 99

S.P = 891

 


Question 2

Find the M.P. when S.P. =₹ 990 and discount = 1%.

Sol :

We know that

\text{Market Price} =\dfrac{ \text{Selling Price}}{\text{100-Discount \%}}\times 100

\text{M.P}=\dfrac{990}{100-1}\times 100

\text{M.P}=\dfrac{990}{99}\times 100

M.P = 1000

 


Question 3

Find the discount, when M.P. = ₹1880 and S.P.= ₹1504.

Sol :

We know that

Selling Price = Market Price – Discount

Discount = Market Price – Selling

Discount = 1880 – 1504

Discount = 376

 


Question 4

A shopkeeper buys a shirt for ₹ 480. A girl buys it from him at a discount of 12\dfrac{1}{2}% on the market price of ₹600. Find the profit percent.

Sol :

Cost of shirt: Rs 480

Market price: Rs 600

Discount given: 12.5% × Rs 600 = Rs 75

Discounted price: Rs 600 – Rs 75 = Rs 525

\text{Profit \%}=\dfrac{\text{total gain}\times 100}{\text{C.P}}

\text{Profit \%}=\dfrac{525-480}{480}\times \text{100\%}

= \dfrac{45}{480} \times \text{100 \%}

=\dfrac{450}{48}

=\dfrac{225}{24}

=\dfrac{225}{24}

=dfrac{75}{8}

=9\dfrac{3}{8}

or

= 9.375%

 


Question 5

Amit purchased a flat for ₹ 7,56,000 and spent ₹ 44,000 on renovation .He sold it for ₹ 8,48,000.Find profit or loss percentage.

Sol :

Cost Price = 756000 + 44000(renovated)

C.P = 800000

Profit = Selling Price – Cost Price

= 8,48,000 – 8,00,000

= 48,000

 

\text{Profit \%}=\dfrac{\text{Profit}}{\text{C.P}} \times 100

=\dfrac{48000}{800000}\times 100

=\dfrac{48}{8}

= 6%

 


Question 6

The catalogue price of an article is ₹ 16 , but the retailer is allowed a trade discount of 25% .At what price must the retailer sell it to gain 25% of what he pays for it ?

Sol :

Catalog Cost Price = ₹ 16

Selling Price = {16 – ( 25% of 16)}

= ₹ 12

To make 25% gain on what he pays he has to sell it at

=12 + (25% of 12)

= 12 + 3

= ₹ 15

 


Question 7

The price of a plate is slashed from ₹ 850 to ₹ 760 by a shopkeeper.Find the rate of discount.

Sol :

Given that :

Actual price = Rs 850

Price after discount = Rs 760

So , Discount price= Rs ( 850 – 760 )

= Rs 90

 

Now ,

\text{Rate of discount} = \dfrac{\text{Discount Price}}{\text{Actual Price}}\times 100

=\dfrac{90}{850}\times 100

=\dfrac{9000}{850}

=\dfrac{900}{85}

=\dfrac{180}{17}

= 10.06 %

 


Question 8

The market price of a refrigerator is ₹ 15450. A dealer allows two successive discount at 15% and 8% . Find the selling price of refrigerator.

Sol :

Price of Refrigerator = 15450

15% of 15450 = ₹ 2317.5
New cost price =  15450 – 2317.5

= ₹ 13,132.5

8% of 13,132.5 = ₹ 1050.6

New cost price = 13132.5 – 1050.6

= ₹ 12,081.9

Price Customer has to give = ₹ 12,081.9

 


Question 9

Find the single discount equivalent to successive discount of 13% and 15%.

Sol :

Mp = 100

1st discount = 13% of 100 = 13

since, 100 – 13 = 87

2nd discount = 15% of 87 = 13.05

Selling price = 87 – 13.05 = 66.95

Single Equivalent Discount  = MP – SP = 100 – 66.95 = 33.05

Required single discount  = 33.05%

 


Question 10

How much percent above the cost should a dealer mark his goods so that after allowing a discount of 26% on the market price, he gains 20%.

Sol :

Let the CP be Rs. 100 and MP be Rs. x

gain % after discount = 12%

gain = 12% of 100 = Rs. 12

⇒ SP of the article = CP + Gain

= Rs. (100 + 12) = Rs. 112

Discount % = 20%

Discount = 20% of Marked Price

=\dfrac{20}{100}\times \text{x}

=\dfrac{20x}{100}

=\dfrac{x}{5}

as the question says
marked Price – discount = SP

=> x-\dfrac{x}{5} = 112

=> \dfrac{5x-x}{5} = 112

=> \dfrac{4x}{5}=112

=> x=112\dfrac{5}{4} = Rs. 140

marked Price = Rs. 140

amount marked above the CP = MP – CP

= Rs. (140 – 100)

= Rs. 40

∴ % amount marked above the CP

=\dfrac{\text{amount increased}}{\text{Cost price}}\times 100

= 40/100 * 100

= 40%


 

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