Question

In what time will ₹ 8000 amount to ₹ 8405 at 5%per annum interest being compounded half yearly

Answer 1

answer is 2 year

let take amount be 8405
and principal is 8000
rate of interest 5/2 half yearly

8405= 8000[1+5/200] power n

8405/8000 = [40+1/40] power n

1681/1600 = [41/40] power n

[41/40]² = [41/40] power n

at last n = 2 years

Answer 2

Answer:

Step-by-step explanation:

Let,

     Time be n yrs.

Given,

      Principal(P) =8000

      Amount(A) =8405

      Rate of interest(r%) =5%

A/Q,                  

      A=P(1+r%/2)power2n

         

 8405=8000(1+5/200)power2n

8405/8000=(41/40)power2n

  1681/1600=(41/40)power2 (41/40)power2    =(41/40)power2n

Since bases are same

Therefore powers must be equal

2n=2

n   =1

Therefore time(n)=1yrs