Question

at what rate per cent will a sum of rs 64000 be compounded to re 68,921 in three years

Answer 1

we have formula of C.I. as followed--

A=P(1+R÷100)³

where a is amount
p is principal
R is rate
³ is time (t)

now
68921=64000(1+R÷100)³
68921÷64000=(1+R÷100)³
(41÷40)³=(1+R÷100)³
powers same, so base must be equal
therefore,
41/40=1+R/100
41/40-1=R/100
1/40×100=R
5/2 % = Rate