Question Bank • QB_GA_GATE_004 NAT • 2 Marks

Section 8: General Aptitude

Quantitative Aptitude

Subtopic: Data Interpretation

Question Statement:

A sum of money invested under annual compound interest doubles itself in $5\text{ years}$. The number of years required for the principal to become 8 times its initial value at the same interest rate is ________ years (in integer).

Answer Key:

15

Step-by-Step Solution & Explanation

Compound Interest Growth: $(1 + r)^5 = 2 \implies [(1 + r)^5]^3 = 2^3 = 8 \implies (1 + r)^{15} = 8$ Thus, $t = 15\text{ years}$.
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