# Biology Questions Answers

1) If a sum of money doubles itself in 8 years at simple interest, the ratepercent per annum

- 1) 12
- 2) 12.5
- 3) 13
- 4) 13.5

**Ans.**B

**Explanation :**

Let sum = x then Simple Interest = x Rate = (100 * x) / (x * 8) = 12.5

2) At 5% per annum simple interest, Rahul borrowed Rs. 500. What amount will he pay to clear the debt after 4 yea

- 1) 750
- 2) 700
- 3) 650
- 4) 600

**Ans.**D

**Explanation :**

We need to calculate the total amount to be paid by him after 4 years, So it will be Principal + simple interest. So, \begin{aligned} => 500 + \frac{500*5*4}{100} => Rs. 600 \end{aligned}

3) What is the present worth of Rs. 132 due in 2 years at 5% simple interest per an

- 1) 110
- 2) 120
- 3) 130
- 4) 140

**Ans.**B

**Explanation :**

Let the present worth be Rs.x Then,S.I.= Rs.(132 - x) =â€º (x*5*2/100) = 132 - x =â€º 10x = 13200 - 100x =â€º 110x = 13200 x= 120

4) A sum of Rs 12,500 amounts to Rs. 15,500 in the 4 years at the rate of simple interest. Find the rate perc

- 1) 6 %
- 2) 7 %
- 3) 8 %
- 4) 9 %

**Ans.**A

**Explanation :**

\begin{aligned} \text{S.I.} = \frac{P*R*T}{100} \\ => R = \frac{S.I. * 100}{P*T} \end{aligned} So, S.I = 15500 - 12500 = 3000. \begin{aligned} => R = \frac{3000 * 100}{12500*4} = 6\% \end{aligned}

5) The simple interest on a certain sum of money at the rate of 5% p.a. for 8 years is Rs. 840. At what rate of intrest the same amount of interest can be received on the same sum after 5 yea

- 1) 5%
- 2) 6%
- 3) 7%
- 4) 8%

**Ans.**D

**Explanation :**

Here firstly we need to calculate the principal amount, then we can calculate the new rate. \begin{aligned} P = \frac{S.I. * 100}{R*T} \ P = \frac{840 * 100}{5*8} \ P = 2100 \ \text{Required Rate = } \frac{840 * 100}{5*2100} \ R = 8\%\ \end{aligned}

6) Reema took a loan of Rs 1200 with simple interest for as many years as the rate of interest. If she paid Rs. 432 as interest at the end of the loan period, what was the rate of intere

- 1) 5%
- 2) 6%
- 3) 7%
- 4) 8%

**Ans.**B

**Explanation :**

Let rate = R% then Time = R years. \begin{aligned} => \frac{1200*R*R}{100}=432 \=> R^2 = 36 \=> R = 6\% \end{aligned}

7) A man took a loan at rate of 12% per annum simple interest. After 3 years he had to pay 5400 interest. The principal amount borrowed by him w

- 1) Rs 14000
- 2) Rs 15000
- 3) Rs 16000
- 4) Rs 17000

**Ans.**B

**Explanation :**

\begin{aligned} \text{S.I.} = \frac{P*R*T}{100} \\ => P = \frac{S.I. * 100}{R*T} \=> P = \frac{5400 * 100}{12*3} = Rs 15000 \end{aligned}

8) A lent Rs. 5000 to B for 2 years and Rs 3000 to C for 4 years on simple interest at the same rate of interest and received Rs 2200 in all from both of them as interest. The rate of interest per annum

- 1) 9%
- 2) 10%
- 3) 11%
- 4) 12%

**Ans.**B

**Explanation :**

Let R% be the rate of simple interest then, from question we can conclude that \begin{aligned} (\frac{5000*R*2}{100}) + (\frac{3000*R*4}{100}) = 2200 \ <=> 100R + 120R = 2200 \<=> R = 10\% \end{aligned}

9) A lent Rs. 5000 to B for 2 years and Rs 3000 to C for 4 years on simple interest at the same rate of interest and received Rs 2200 in all from both of them as interest. The rate of interest per annum

- 1) 9%
- 2) 10%
- 3) 11%
- 4) 12%

**Ans.**B

**Explanation :**

Let R% be the rate of simple interest then, from question we can conclude that \begin{aligned} (\frac{5000*R*2}{100}) + (\frac{3000*R*4}{100}) = 2200 \ <=> 100R + 120R = 2200 \<=> R = 10\% \end{aligned}

10) What will the ratio of simple interest earned by certain amount at the same rate of interest for 6 years and that for 9 yea

- 1) 1:2
- 2) 2:1
- 3) 2:2
- 4) 2:3

**Ans.**D

**Explanation :**

Let the principal be P and rate be R then \begin{aligned} \text{ratio = } [\frac{(\frac{P*R*6}{100})}{(\frac{P*R*9}{100})}] \ = \frac{6PR}{9PR} = 2:3 \end{aligned}