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A certain sum of money amounts to Rs. 2200 at 5% p.a. rate of interest, Rs. 2320 at 8% interest in the same period of time. The period of time is :
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- 3 years
- 4 years
- 5 years
- 2 years
- 3 years
Correct Option: D
Let Principal = Rs. P and time = T years
Rate = 5%
∴ SI = | |
100 |
According to the question,
∴ P + | = 2200 | |
100 |
&rArr4; P + | = 2200...........(i) | |
100 |
Again, | - | = 2320 – 2200 | ||
100 | 100 |
⇒ | = 120 | |
100 |
⇒ PT = | = 4000............(ii) | |
3 |
∴ From equation (i),
P + | = 2200 | |
20 |
⇒ P = 2200 – 200 = Rs. 2000
∴ From equation (ii),
PT = 4000
⇒ T = | = 2 Year | |
2000 |
Second method to solve this question :
Difference in rates = 8 – 5 = 3%
∵ 3% = 2320 – 2200 = 120
∴ 5% ≡ | × 5 = 200 | |
3 |
∴ Principal = Rs. (2200 – 200) = Rs. 2000
∴ Time = | = 2 Years | |
2000 × 5 |