Question

Ratio of the principal and amount after 3year is 20:29find the rate of interest per annum.
15% , 17%, 18% , 12%​

Answer 1

Answer:

15%

Step-by-step explanation:

20 becomes 29 after 3 y.

Case 1:

if int is simple int,

i= 3 per year

and rate is (3/20)*100=15%

Case 2: compound int:

i=9 for 3 years

A=P(1+r/100)^n

29=20(1+r/100)^3

29/20=(1+r/100)^3

(29/20)^(1/3)=(1+r/100)

=(100+r)/100

1.45^(1/3) =(100+r)/100

1.1318 =(100+r)

r =1.1318-100

Negative interest.