At six months’ intervals A deposited of Rs. 1000 in a savings account which credit interest at 10% p.a.,
compounded semi-annually. The first deposit was made when A’s son was 6 months old and last deposit
was made when his son was 8 years old. The money remained in the account and was presented to the
son on his 10th birthday. How much did he receive?

 

(a) Rs.25740
(b) Rs.23740
(c) Rs.25860
(d) Rs.25760

Ans 
Hello student 
so from the question it is given that the , 
Deposited on 6 Months   Received on 10 Years

interest earned for  114 months = 19 * 6 Months

Deposited on 12 Months Received on 10 Years

interest earned for  108 months = 18 * 6 Months

Deposited on 8 Years (96 months) Received on 10 Years

interest earned for  24 months = 4 * 6 Months

Amount Deposited every time = Rs 1000

Rate of interest = 10 % PA = 5% for 6 months

Amount  = 1000 * (  1.05¹⁹ + 1.05¹⁸ + ............................................+ 1.05⁴)

= 1000 * 1.05⁴(1 + 1.05 +....................................................+ 1.05¹⁴ + 1.05¹⁵)

= 1000 * 1.05⁴ ( 1.05¹⁶ - 1)/(1.05 - 1)

= 1000 * 1.05⁴ (2.1829 - 1)/(0.05)

= 28786

Thanks and Regards ,
Harshit Tyagi 

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