A sum of RS. 400 amounts to RS. 441 in 2 yr. What will be its amount, if the rate of interest is increased by 5%?

A) RS.484

B) RS.560

C) RS.512

D) RS.560

Correct answer:
A) RS.484

Description for Correct answer:
According to the given conditign

441=\( \Large 400 \left(1+ \frac{R}{100}\right)^{2} \)

=> \( \Large \frac{441}{400} \)= \( \Large \left(1+ \frac{R}{100}\right)^{2} \)

=> \( \Large \left(\frac{21}{20}\right)^{2} \)=\( \Large \left(1+ \frac{R}{100}\right)^{2} \)

=> \( \Large \frac{21}{20} \)=\( \Large 1+ \frac{R}{100} \)

=> \( \Large \frac{21}{20}-1=\frac{R}{100} \) => \( \Large \frac{R}{100}=\frac{1}{20} \)

R=5%

New rate = 5+5=10%

Amount=\( \Large 400 \left(1+ \frac{10}{100}\right)^{2} \)

=\( \Large 400\times 11/10\times 11/10 \)=RS.484


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