7th Maths : Term 3 Unit 2 : Percentage and Simple Interest : Simple Interest : Exercise 2.4 : Text Book Back Exercises Questions with Answers, Solution

**Exercise
2.4**

** **

**1. Find the simple interest on ₹ 35,000
at 9% per annum for 2 years?**

**Solution: **

Principal P = ₹ 35,000

Rate of interest *r *=
9% per annum

Time (*n*) = 2 years

Simple Interest I = P*nr*
/ 100 = (35000 × 2 × 9) / 100 = ₹ 6300

Simple interest I = ₹ 6300

** **

**2. Aravind borrowed a sum of ₹ 8,000
from Akash at 7% per annum. Find the interest and amount to be paid at the end of
two years.**

**Solution: **

Here Principal P = ₹ 8,000

Rate of interest* r* =
7% per annum

Time (*n*) = 2 years

Simple Interest (I) = P*nr*
/ 100 = ( 8000 × 2 × 7) / 100

I = ₹ 1120

Amount = P + I

I = ₹ 8000 + 1120 = 9120

Interest to be paid = ₹ 1,120

Amount to be paid = ₹ 9120

** **

**3. Sheela has paid simple interest on
a certain sum for 4 years at 9.5% per annum is ₹ 21,280. Find the sum.**

**Solution: ** Let the Principal be ₹ P

Rate of interest *r *= 9.5%
per annum

Time (*n*) = 4 years

Simple Interest I = P*nr*
/ 100

Given I = ₹ 21,280

∴ P*nr* / 100 = ₹ 21,280

[P × 4 × 95] / 100 = ₹ 21,280

[P × 4 × 95] / 1000 = ₹ 21,280

P = (21280 × 1000) / 4 × 95 = ₹ 56,000

∴ Sum of money Sheela bought = ₹ 56,000

** **

**4. Basha borrowed ₹ 8,500 from a bank
at a particular rate of simple interest. After 3 years, he paid ₹ 11,050 to settle
his debt. At what rate of interest he borrowed the money?**

**Solution: **

Let the rate of interest be *r*%
per annum

Here Principal P = ₹ 8500

Time *n* = 3 years

Total amount paid = ₹ 11,050

A = P + I = ₹ 11,050

i.e. 8,500 + 1 = ₹ 11,050

1 = ₹ 11,050 – ₹ 8,500 = ₹ 2,550

Also we know that I = P*nr*
/ 100 = ₹ 2,550

[ 8,500 × 3 × *r* ] / 100
= ₹ 2,550

*r *= (2,550 × 100) / (8500 × 3)

*r *= 10%

Rate of interest r = 10%

** **

**5. In What time will ₹ 16,500 amount
to ₹ 22,935 at 13% per annum?**

**Solution: **

Rate of interest* r* =
13% per annum

Here Amount A = ₹ 22,935

Principal P = ₹ 16,500

A = P + I

22935 = 16,500 + I

∴ Interest I = 22935 – 16,500 = ₹ 6,435

Simple Interest I = P*nr*
/ 100

6435 = (16500 × *n* × 13)
/ 100

*n *= (6435 × 100) / (16500 × 13)

*n *= 3 years

Required time *n *= 3
years

** **

**6. In what time will ₹ 17800 amount to
₹ 19936 at 6% per annum?**

**Solution: **

Let the require time be *n *years

Here Principal P = ₹ 17,800

Rate of interest *r* =
6% per annum

Amount A = ₹ 19,936

A = P + I

19936 = 17800 + I

19936 – 17800 = I

2136 = I

Simple Interest (I) = P*nr*
/ 100

2136 = [ 17800 × *n* × 6
] / 100

*n *= (2136 × 100) / (17800 × 6)

*n *= 2 years

Required time = 2 years

** **

**7. A sum of ₹ 48,000 was lent out at
simple interest and at the end of 2 years and 3 months the total amount was ₹ 55,560.
Find the rate of interest per year.**

**Solution: **

Given Principal P = ₹ 48,000

Time *n* = 2 years 3
months

= 2 + (3/12) years = 2 + (1/4)
years

= 8/4 + 1/4 years = 9/4
years

Amount A = ₹ 55,660

A = P + I

55660 = 48000 + I

I = 55660 – 48000 = ₹ 7660

∴ Interest for 9/4 years = ₹ 7660

Simple Interest = P*nr*
/ 100

7660 = 48000 × 9/4 × *r*/100

* r = *(7660 × 4 × 100) / (9
× 48000) = 7.09% = 7%

Rate of Interest = 7% per annum

** **

**8. A principal becomes ₹ 17,000 at the
rate of 12% in 3 years. Find the principal.**

**Solution: **

Given the Principal becomes ₹ 17,000

Let the principle initially be P

Rate of Interest *r* = 12%
per annum

Time *n* = 3 years

According to the problem given I = 17000 – P = [ P × 3 × 12 ] /
100

17000 = (36/100) P + P

17000 = P ( 36/100 + 1 )

17000 = P ( 136 / 100 )

P = (17000 × 100) / 136 = 12,500

∴ Principal P = ₹ 12,500

** **

__Objective type Questions.__

**9. The interest for a principle of ₹ 4,500
which gives an amount of ₹ 5,000 at end of certain period is**

(i) ₹ 500

( ii) ₹200

( iii) 20%

(iv) 15%

**[Answer: (i) ₹ 500]**

**Solution:
**Interest = Amount –
Principle = ₹ 5000 – ₹4500 = ₹ 500

**10.
Which among the following is the simple interest for the principle of ₹ 1,000 for
one year at the rate of 10% interest per annum?**

(i) ₹ 200

( ii) ₹10

( ii) ₹100

( ii) ₹1,000

**[Answer: (iii) ₹100]**

**Solution:
**Interest = P*nr* / 100 = [1000×1×10] / 100 = ₹ 100

**11.
Which among the following rate of interest yields an interest of ₹ 200 for the principle
of ₹ 2,000 for one year.**

(i) 10%

(ii) 20%

(iii) 5%

(iv) 15%

**[Answer: (i) 10%]**

**Solution : **

__ANSWERS:__

**Exercise 2.4 **

1. ₹ 6,300

2. I= ₹ 1,120 ; A = ₹ 9,120

3. ₹ 56,000

4. 10%

5. 3 years

6. 2 years

7. 7%

8. ₹ 12,500

** Objective type questions **

9. (i) ₹ 500

10. (iii) ₹ 100

11. (i) 10%

Tags : Term 3 Chapter 2 | 7th Maths , 7th Maths : Term 3 Unit 2 : Percentage and Simple Interest

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7th Maths : Term 3 Unit 2 : Percentage and Simple Interest : Exercise 2.4 (Simple Interest) | Term 3 Chapter 2 | 7th Maths

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