1. The simple interest on a certain sum for 8 months at 4% per annum is Rs. 129 less than the simple interest on the same sum for 15 months at 5% per annum. The sum is:

1. Rs. 2580

2. Rs. 2400

3. Rs. 2529

4. Rs. 3600

5. None of these

Answer & Explanation

Answer:- 4

Explanation :-

Let the sum be Rs. x

Given That [(x*5*15)/(100*12)] – [(x*4*8)/(100*12)] = 129

75x – 32x = 129 (100*12)

x = (120*1200) / 43

x = Rs. 3600

2. A person deposited Rs. 400 for 2 years, Rs. 550 for 4 years and Rs. 1,200 for 6 years. He received the total simple interest of Rs. 1,020. The rate of interest per annum is ?

1. 10%

2. 5%

3. 15%

4. 20%

5. None of these

Answer & Explanation

Answer:- 1

Explanation :-

Let Rate of interest be R%

SI(1) = (400*2*R)/100, SI(2) = (550*4*R)/100, SI(3) = (400*6*R)/100

Total SI = SI(1) + SI(2) + SI(3) = 1020

[(400*2*R)/100] + [(550*4*R)/100] + [(400*6*R)/100]
8R + 22R +72R = 1020

102R = 1020

R = 10%

3. A sum of money becomes 7/6 of itself in 3 years at a certain rate of simple interest. The rate per annum is?

1. 5 5/9%

2. 6 5/9%

3. 18%

4. 25%

5. None of these

Answer & Explanation

Answer:- 1

Explanation :-

Let Principal be P & Rate be R%

Amount (A) = (7/6)P

Therefore, SI = [(7/6)P] – P = P/6

SI =(PRT)/100

P/6 = (P*R*3)/100

R= 50/9 = (5+ 5/9 )%

4. At what rate per cent per annum will the simple interest on a sum of money be 2/5 of the amount in 10 years?

1. 4

2. 6

3 5 2/3

4. 6 2/3

5. None of these

Answer & Explanation

Answer:- 1

Explanation :-

Let the Sum be Rs.x and rate = R%

(2/5)x = (x*R*10)/100

R = 200/(5*10)

R = 4%

5. Simple interest on a certain sum for 6 years is 9/25 of the sum. The rate of interest is ?

1. 6%

2. 6 1/2%

3. 8%

4. 8 1/2%

5. None of these

Answer & Explanation

Answer:- 1

Explanation :-

Let the Sum be Rs.x and rate = R%

(9/25)x = (x*R*6)/100

R = 900/(6*25)

R = 6%