1. A tree increases annually by 1⁄5 th of its height. If its height today is 50 cm, what will be the height after 2 years?

1. 64 cm

2. 72 cm

3. 66 cm

4. 84 cm

Answer & Explanation

Answer:- 2

Explanation :-

Present height = 50 cm , Time = 2 years

Rate of increase = (1/5)×100 = 20%

Height after 2 years = P(1+R/100)^T

=> 50(1+20/100)^2 = 50(1+1/5)^2 = 50(6/5)^2

=> (50×6×6)/(5×5) = 72 cm

2. On a sum of money, the simple interest for 2 years is Rs. 320, while the compound interest is Rs. 340, the rate of interest being the same in both the cases. The rate of interest is:

1. 15%

2. 14.25%

3. 12.5%

4. 10.5%

Answer:- 3

Explanation :-

Difference between the CI and SI = (R×SI)/(2×100)

Difference between the CI and SI = 340 – 320 = 20

Therefore, (R×SI)/(2×100) = 20R = (20*2*100) / 320

R = 12.5%

3. A bank offers 10% interest rate compounded annually. A person deposits Rs. 20,000 every year in his account. If he does not withdraw any amount, then how much balance will his account show after four years?

1. Rs. 102102

2. Rs. 102220

3. Rs. 104202

4. Rs. 104222

Answer & Explanation

Answer:- 1

Explanation :-

Answer:- Amount after 1 years =20000 + 10% of 20000 = 20000+ 2000 = Rs. 22000

Amount after 2 years = 20000 + 22000 + 10% of 22000 = Rs. 46200

Amount after 3 years = 20000 + 46200+ 10% of 46200 = Rs.72820

Amount after 4 years = 20000 +.72820 + 10% of 72820 = Rs.102102

4. A sum of money becomes Rs. 2200 after three years and Rs. 4400 after six years on compound interest. The sum is

1. Rs. 1400

2. Rs. 1100

3. Rs. 1000

4. Rs. 1200

Answer & Explanation

Answer:- 2

Explanation :-

Let the sum be P and rate of interest be R% per annum.

Amount after 3 years = 2200

P(1+R/100)^T = 2200

P(1+R/100)^3 = 2200 ——-— (1)

Amount after 6 years = 4400

P(1+R/100)^T = 4400

P(1+R/100)^6 = 4400 ——-— (2)

Dividing (2) by (1)

[P(1+R/100)^6] / [P(1+R/100)]^3 = 4400/2200 = 2

(1+R/100)^3 = 2

put this value in equation (1)

P × 2 = 2200

P = 2200/2 = Rs.1100

5. What annual payment will discharge a debt of Rs. 1025 due in 2 years at the rate of 5% compound interest?

1. Rs. 560

2. Rs. 560.75

3. Rs. 551.25

4. Rs. 550

Answer & Explanation

Answer:- 3

Explanation :-

Present Worth = x / (1+R/100)^T

1025 = Present Worth of Rs. x due 1 year hence + Present Worth of Rs.x due 2 year hence

1025 = x/(1+5/100)^1 + x/(1+5/100)^2

1025 = x/(105/100 ) + x/(105/100)^2

1025 = x/(21/20) + x/(21/20)^2

1025 = [(x × 20)/21] + [(x × 20 × 20)/(21×21)]

1025 = (20x/21) + (400x/441 )

820x/441 = 1025

x=(1025 × 441) / 820 = (205×441)/164 = Rs. 551.25