Question

(d) Rs. 720
0
If Rs. 64 amount to Rs. 83.20 in 2 years, what will Rs. 86 aurouat to
in 4 years at the same rate per cent per annum ?​

Answer 1

Answer:

C) Rs.137.60

Description for Correct answer:

let the rate of interest = R% 

According to question 

Intrest in 2 yrs = 83.20−64=19.2083.20−64=19.20

R(in per)=SI×100P×TSI×100P×T

R(in per)=19.20×10064×219.20×10064×2

R(in per)=302302=15%

Therefore, Amount of Rs.86 will be in four years by 15(in per) rate of interest

SI=86×15×410086×15×4100= Rs.51.6

Amount=Principal+S.IPrincipal+S.I

=86+51.686+51.6=Rs. 137.60

Answer 2

Correct question!!

If Rs 64 amount to Rs 83.20 in 2 years, what will Rs 86 amount to in 4 years at the same rate per cent per annum?

Solution!!

• Principal (P) = Rs 64

• Amount = Rs 83.20

• Time (T) = 2 years

• Rate of interest (R) = ?

• Amount = Principal + Interest

→ Rs 83.20 = Rs 64 + Interest

→ Interest = Rs 83.20 - Rs 64

• Interest = Rs 19.2

• Interest = (P × R × T)/100

→ 19.2 = (64 × R × 2)/100

→ 1920 = 64 × 2 × R

→ 1920 = 128 × R

→ R = 1920 ÷ 128

• R = 15%

In the second case,

• Principal (P) = Rs 86

• Rate of interest (R) = 15%

• Time (T) = 4 years

• Interest = (P × R × T)/100

→ Interest = (86 × 15 × 4)/100

→ Interest = 5160/100

• Interest = Rs 51.6

• Amount = Principal + Interest

→ Amount = Rs 86 + Rs 51.6

• Amount = Rs 137.6