Question

A sum of money becomes triples itself in 8 years under simple interest at certain rate of interest. How many times it becomes itself in 20 years under SI at the rate of interest? (1) 5 (2) 6 (3) 4 (4) 7 (5) NOTA

Answer 1

LET PRINCIPAL AMT=a
MATURITY VALUE AFTER 8 YEARS=3a
i.e. SIMPLE INTT IN 8 YRS=3a-a=2a
i.e. INTT RATE=(2ax100)/8a=25%
i.e. INTT IN 20 YRS=ax25x20/100=5a
i.e. MATURITY VALUE AFTER 20 YRS=a+5a=6a
i.e. IT WILL BECOME 6 TIMES IN 20 YRS