A bank offers 5% compound interest calculated on half-yearly basis. A customer deposits Rs. 1600 each on 1st January and 1st July of a year. At the end of the year, the amount he would have gained by way of interest is:
120
121
122
123
Explanation:
Amount = Rs. $\left[ 1600 X \left( 1+\dfrac{5}{2 X 100} \right)^{2} \left( 1+\dfrac{5}{2 X 100} \right) \right]$
= Rs. $\left[ 1600 X \dfrac{41}{40} X \dfrac{41}{40} +1600 X \dfrac{41}{40} \right]$
= Rs. $\left[ 1600 X \dfrac{41}{40} \left( \dfrac{41}{40} + 1\right) \right]$
= Rs. $\left[\dfrac{1600X41X81}{40X40} \right]$
= Rs. 3321.
C.I. = Rs. (3321 - 3200) = Rs. 121
Amount = Rs. $\left[ 1600 X \left( 1+\dfrac{5}{2 X 100} \right)^{2} \left( 1+\dfrac{5}{2 X 100} \right) \right]$
= Rs. $\left[ 1600 X \dfrac{41}{40} X \dfrac{41}{40} +1600 X \dfrac{41}{40} \right]$
= Rs. $\left[ 1600 X \dfrac{41}{40} \left( \dfrac{41}{40} + 1\right) \right]$
= Rs. $\left[\dfrac{1600X41X81}{40X40} \right]$
= Rs. 3321.
C.I. = Rs. (3321 - 3200) = Rs. 121