Question

At what rate of simple intrest will a sum of money double itself in 20 year?

Answer 1

RATE -?
LET SUM BE ' X'.
TIME- 20 YRS
AMOUNT-2×X =2X
INTEREST =2X-X=X
WE KNOW
R=(INTEREST ×100)÷SUM×TIME=
(X×100)÷X×20=5%
at 5% rate of interest SUM will double itself in 20 yrs....