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Aptitude - Compound Interest - Discussion

Discussion Forum : Compound Interest - General Questions (Q.No. 1)
Compound Interest
1.
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:
Rs. 120
Rs. 121
Rs. 122
Rs. 123
Answer: Option
Explanation:
Amount
= Rs. 1600 x 1 + 5 2 + 1600 x 1 + 5
2 x 100 2 x 100
= Rs. 1600 x 41 x 41 + 1600 x 41
40 40 40
= Rs. 1600 x 41 41 + 1
40 40
= Rs. 1600 x 41 x 81
40 x 40
= Rs. 3321.

C.I. = Rs. (3321 - 3200) = Rs. 121

Discussion:
220 comments Page 1 of 22.
Akhila said:   2 decades ago
How did you get 41/40 am not able to get that value please help me.
Sundar said:   2 decades ago
Hi Akhila,

= 1 + (5/(2 x 100)

= 1 + (5/200)

= 1 + (1/40)

= (40 + 1)/40

= 41/40

Next step (41/40)^2

= 41/40 x 41/40
...

Hope you understand. Have a nice day!
SIPU said:   1 decade ago
YA SUNDER IS CORRECT...
Bala said:   1 decade ago
Its a basic thing. Where did you get 3200 in this problem?
Manju said:   1 decade ago
Hai, where did you get from this value 3200.
Dinesh guptha said:   1 decade ago
I think customer deposits per year 3200.

So they subtracted 3200 with that final amount it seems.
Dinesh said:   1 decade ago
Can anyone clear me the first step.
Venkat said:   1 decade ago
venkst:simple customer deposited twice
1600*2=3200
Boney said:   1 decade ago
I dont understand the 2nd term in the expression
Amount=1600[1+(1/2)*(5/100)]^2+ 1600[1+(5/2*100)]
Amount compounded half yearly is A=P[1+r/2*100)]^2
Don't understand what this term doing 1600[1+(5/2*100)]
Someone tell me
(1)
Lavanya said:   1 decade ago
I too dint understand d first step
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