Question

what rate a sum doubles itself in 8years 4months

Answer 1

2p=pr(25/3)....(i.e. 8 years and 4 months= 25/3 of a year)
2=25p/3
6=25r
6/25=r
24%=r

3p=(0.24)t
3=0.24t
12.5=t

Hope this helps you!! :)

Answer 2

let
total amount = p
rate = r %
given that
time = 8 years 4 month
= 25/3 year

now,

$(p \times r \times 25) \div 300 = 2p \\ or \: r \: = 600 \div 25 \\ or \: r = 24$
In 24% rate a sum doubles itself in 8 years 4 months.