# A bank offers 5% compound interest calculated on half-yearly basis. A customer deposits Rs. 1600 each on 1^{st} January and 1^{st} July of a year. At the end of the year, the amount he would have gained by way of interest is:

A. Rs. 120

B. Rs. 121

C. Rs. 122

D. Rs. 123

E. None of these

**Answer: Option B **

__Solution(By Examveda Team)__

$$\eqalign{
& {\text{Amount}} \cr
& = {1600 \times {{\left( {1 + \frac{5}{{2 \times 100}}} \right)}^2} + 1600 \times \left( {1 + \frac{5}{{2 \times 100}}} \right)} \cr
& = {1600 \times \frac{{41}}{{40}} \times \frac{{41}}{{40}} + 1600 \times \frac{{41}}{{40}}} \cr
& = {1600 \times \frac{{41}}{{40}}\left( {\frac{{41}}{{40}} + 1} \right)} \cr
& = {\frac{{1600 \times 41 \times 81}}{{40 \times 40}}} \cr
& = Rs.\,3321 \cr
& \therefore C.I. = Rs.\,\left( {3321 - 3200} \right) \cr
& \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = Rs.\,121 \cr} $$ ## Join The Discussion

## Comments ( 2 )

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