A sum of money at simple interest doubles in 7 years. It will become four times in

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RRB TC CC Exam (Patna) 2006 click here to view all questions

A sum of money at simple interest doubles in 7 years. It will become four times in

A90 years

B18 years

C38 years

D21 years

Akilesh Kharvi ? Nov 5 '2016 at 10:48

Answer is : 21 years

let sum=x, s.i. = x

rate = \(100 * x \over x * 7\) = \(\frac{100}{7}\% \)

now,

sum = x, s.i. = 3x, rate = \(\frac{100}{7}\%\)

time = \(\frac{100 * 3x}{\frac{x * 100}{7}}\%\)

\(=> 7 *3 \%\)

=21 %

All DiscussionsClick here to write answer

Answer is : 21 years let sum=x, s.i. = x rate = \(100 * x \over x * 7\) = \(\frac{100}{7}\% \) now, sum = x, s.i. = 3x, rate = \(\frac{100}{7}\%\) time = \(\frac{100 * 3x}{\frac{x * 100}{7}}\%\) \(=> 7 *3 \%\) =21 % Akilesh Kharvi ? answered Nov 5 '2016 at 10:48 All Comments

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