### NCERT Solutions for Class 7 Maths Chapter 8 Comparing Quantities Ex 8.3

**Ex 8.3 Class 7 Maths Question 1.**

**Tell what is the profit or loss in the following transactions. Also find profit per cent or loss per cent in each case.**

**(a) Gardening shears bought for ₹ 250 and sold for ₹ 325.**

**(b) A refrigerator bought for ₹ 12,000 and sold at ₹ 13,500.**

**(c) A cupboard bought for ₹ 2,500 and sold at ₹ 3,000.**

**(d) A skirt bought for ₹ 250 and sold at ₹ 150.**

**Solution:**

(a) Here, CP = ₹ 250

SP = ₹ 325

Since SP > CP

∴ Profit = SP – CP

= ₹ 325 – ₹ 250 = ₹ 75

Hence, the required profit = ₹ 75

and Profit per cent = 30%

(b) Here, CP = ₹ 12,000

SP = ₹ 13,500

Since SP > CP

∴ Profit = SP – CP

= ₹ 13,500 – ₹ 12,000 = ₹ 1,500

Hence, the required profit = ₹ 1500 × 100

profit % = %

(c) Here, CP = ₹ 2500

SP = ₹ 3000

Since SP > CP

∴ Profit = SP – CP

= ₹ 3000 – ₹ 2500 = ₹ 500

Hence, the required profit = ₹ 500 and profit% = 20%

(d) Here, CP = ₹ 250

SP = ₹ 150

Here CP > SP

∴ Loss = CP – SP

= ₹ 250 – ₹ 150 = ₹ 100

Hence, the required loss = ₹ 100 and loss% = 40%

**Ex 8.3 Class 7 Maths Question 2.**

**Convert each part of the ratio to Percentage:**

**(a) 3:1**

**(b) 2:3:5**

**(c) 1 : 4**

**(d) 1:2:5**

**Solution:**

(a) 3 : 1

Sum of the ratio parts = 3 + 1 = 4

(b) 2 : 3 : 5

Sum of the ratio parts = 2 + 3 + 5 = 10

(c) 1 : 4

Sum of the ratio parts =1 + 4 = 5

(d) 1 : 2 : 5

Sum of the ratio parts = 1 + 2 + 5 = 8

**Ex 8.3 Class 7 Maths Question 3.**

**The population of a city decreased from 25,000 to 24,500. Find the Percentage decrease.**

**Solution:**

Initial population = 25,000

Decreased population = 24,500

Decrease in population

= 25,000 – 24,500 = 500

Percentage of decrease = 500 × 100/25000 = 2%

Hence the Percentage of decrease in population = 2%.

**Ex 8.3 Class 7 Maths Question 4.**

**Arun bought a car for ₹ 3,50,000. The next year, the price went upto ₹ 3,70,000. What was the Percentage of price increase?**

**Solution:**

Original price of the car = ₹ 3,50,000

Price increased next year = ₹ 3,70,000

Increase in price = ₹ 3,70,000 – ₹ 3,50,000

= ₹ 20,000

∴ Percentage of the increase in the price

Hence, the Percentage of increase in price

=

**Ex 8.3 Class 7 Maths Question 5.**

**I buy a TV for ₹ 10,000 and sell it at a profit of 20%. How much money do I get for it?**

**Solution:**

Here, CP = ₹ 10,000

Profit = 20%

SP = ?

Hence, the required money got by me = ₹ 12,000.

**Ex 8.3 Class 7 Maths Question 6.**

**Juhi sells a washing machine for ₹ 13,500. She loses 20% in the bargain. What was the price at which she bought it?**

**Solution:**

SP of the washing machine = ₹ 13,500

Loss = 20%

CP = ?

Hence, the cost price of the machine = ₹ 16875.

**Ex 8.3 Class 7 Maths Question 7.**

**(i) Chalk contains calcium, carbon and oxygen in the ratio 10 : 3 : 12. Find the Percentage of carbon in chalk.**

**(ii) If in a stick of chalk, carbon is 3 g, what is the weight of the chalk stick?**

**Solution:**

(i) Sum of the ratio parts = 10 + 3 + 12 = 25

∴ Percentage of carbon in chalk

= 3/25 × 100% = 12 %

Hence, the Percentage of carbon in chalk = 12%

(ii) Weight of carbon = 3 g

∴ Weight of chalk = 3/3 × 25 g = 25 g

Hence, the weight of chalk = 25 g

**Ex 8.3 Class 7 Maths Question 8.**

**Amina buys a book for ₹ 275 and sells it at a loss of 15%. How much does she sell it for?**

**Solution:**

CP of book = ₹ 275

Loss = 15%

Hence, the required selling price = ₹ 233.75

**Ex 8.3 Class 7 Maths Question 9.**

**Find the amount to be paid at the end of 3 years in each case.**

**(a) Principal = ₹ 1200 at 12% p.a.**

**(b) Principal = ₹ 7500 at 5% p.a.**

**Solution:**

(a) Given: Principal = ₹ 1200

Rate of interest = 12% p.a., T = 3 years

∴ Interest = P × R × T/100 = 1200 × 12 × 3/100

Amount = Principal + Interest

= ₹ 1200 + ₹ 432 = ₹ 1632

Hence, the required amount = ₹ 1632

(b) Given: Principal = ₹ 7500

Rate = 5% p.a.

Time = 3 years

∴ Interest = P × R × T/100 = 7500 × 5 × 3/100

= ₹1125

Amount = Principal + Interest

= ₹ 7500 + 11125 = ₹ 8625

Hence, the required amount = ₹ 8625.

**Ex 8.3 Class 7 Maths Question 10.**

**What rate gives ₹ 280 as interest on a sum of ₹ 56,000 in 2 years?**

**Solution:**

Given: Principal = ₹ 56,000

Interest = ₹280

Time = 2 years

Rate = ?

Hence, the required rate = 0.25%

**Ex 8.3 Class 7 Maths Question 11.**

**If Meena gives an interest of ₹ 45 for one year at 9% rate p.a. What is the sum she has borrowed?**

**Solution:**

Given: Interest = ₹ 45

Time = 1 year

Rate = 9% p.a.