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A sum doubles itself in 16 years, then in how many years will it triple itself; rate of interest being simple
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- 25 years
- 24 years
- 48 years
- 64 years
- None of these
- 25 years
Correct Option: E
Let Principal = Rs. p and Simple Interest = Rs. p
Rate = | |
Principal × Time |
Rate = | = | % per annum | ||
p × 16 | 4 |
Case II,
Interest = Rs. 2p
∴ Time = | |
Principal × Rate |
Time = | = 32 year. | |
p × 25 |
Second method to solve this question :
Here , n = 2
R = | × 100% | |
T |
R = | × 100 | |
16 |
R = | % | |
4 |
R = 6 | % | |
4 |
Now, T = | × 100 | |
R |
Here , n = 3
T = | × 100 | |
( 25/4 ) |
T = | = 32 years. | |
25 |