Question

A sum of money triples itself at 8% per annum over a certain time. The time take is ?

Answer 1

Acc. to question,

let the some of money be x

then amount will be 3x

rate = 8%

let time be t

then, A = P + I

or, 3x = x + (x * 8 * t)/100

or, 2x = 8xt/100

or, 8xt = 200x

or, t = 200x/8x

or, t  = 25yrs (Ans)

Answer 2

Let sum of money is P
after T years , sum of money will be 3P as according to question,
rate per annum = 8 %

we know,
SI = P × R × T /100
= P × 8 × T/100

final sum of money = simple interest + initial sum of money
3P = SI + P
2P = P × 8 × T/100
2 = 8T/100
T = 200/8 = 25

hence, after 25 years sum of money will be triple itself .