Aptitude - Compound Interest - Discussion

Discussion Forum : Compound Interest - General Questions (Q.No. 1)
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 12 of 22.

Gurpreet said:   1 decade ago
Because 3200 is the total amount of one year which is principle.

Thirumurugan sundaram said:   1 decade ago
I think it will be as correct answer for everyone, the first deposit amt is 1600, after six month total amt is 1640 (Including 5% of one year interest for six months). We should assign this as A-case.

Next July 1st day second deposit amt is 1600, It should be as B-case. The end of the year amt is 1640 (Including 5% of one year interest of six months). But A-case deposited at one year, So total Mature amt is 1681 (Including 5% of one year interest of twelve months. Interest of Rs. 40 is Rs-1, So amt Rs-40 became as Rs-41).

Finally A-case + B-case are 1681 + 1640 = 3321. Deposit amt is Rs-3200 and Interest amt is Rs-121.

PRASOON DAWN said:   1 decade ago
I am not able to understand the problem in these quick steps. Can anyone please help me understand in detailed process.

Prathik said:   1 decade ago
Guys most of you might be confused with the formula, lets do this way:

1st 6 months deposit = 1600,

Interest earned at 5% upto July = (1600 x 5/100 x 1/2) = 40.

Note: In compound interest interest gets added to the principle.

So P = 1640 now, and next deposit in July = 1600.

Total deposit = (1640+1600), interest = (3240 x 5/100 x 1/2) = 81.

Total profit earned as interest = 40+81 = 121.

Hope this helps.

Anna said:   1 decade ago
Your answer are so useful guys. Keep it up.

Swarna said:   1 decade ago
Such a brilliant answers I got here. How you people can make this possible?

Please give some suggestion to improve my aptitude problem solving ability.

Dias said:   1 decade ago
Is there any other way to solve this problem?

Monalisa said:   1 decade ago
I am confused somebody help me a better way to do this problem?

Anu said:   1 decade ago
1600+1600 = 3200.

Nidhi said:   1 decade ago
Thanks @Anu you explain it nicely.

Here half yearly means every six months so the amount of 1600 is submitted two times so that it become 3200.

Thank you all have a good day.


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