UP TGT Mathematics Commercial mathematics Test Series - Part 2
With a given rate of simple interest, the ratio of principal and amount for a certain period of time is 4 : 5. After 3 y...
Type: MCQ • Marks: 1
With a given rate of simple interest, the ratio of principal and amount for a certain period of time is 4 : 5. After 3 years, with the same rate of interest, the ratio of principal and amount becomes 5 : 7. The rate of interest per annum is:
Options
A. 1) 7%
B. 2) 8%
C. 3) 6.67%
D. 4) 5%
Explanation
Initially, Principal : Amount = 4 : 5 = 20 : 25.
After 3 years, Principal : Amount = 5 : 7 = 20 : 28.
In 3 years, interest added = 28 - 25 = 3 units on principal 20.
1 year interest = 1 unit.
Rate = (1 / 20) * 100 = 5%... Wait! Let's recheck calculation: 1/20 * 100 = 5%.
Let's verify: P=20, initially A=25 (5 yrs @ 5%). After 3 yrs, A=28 (8 yrs @ 5%). Ratio 20:28 = 5:7. Perfect! Correct Option: 5%.
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