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SSC CGL 2022 PYQ — Question 69

SSC CGL - 01 Dec 2022 - Shift 1 • Quantitative Aptitude • Q69

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Which of the following numbers is a divisor of (4915 – 1)?

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Correct answer: C

Explanation

The correct answer is Option 3. i.e.8.

According to concept,

(4915−1)⇒((72)15−1)⇒(730−1) \begin{aligned} & \left(49^{15}-1\right) \\ & \Rightarrow\left(\left(7^2\right)^{15}-1\right) \\ & \Rightarrow\left(7^{30}-1\right) \end{aligned}

Here, 30 is a positive integer.
According to the concept,

(730−1) \left(7^{30}-1\right) is divisible by (7+1) i.e., 8 .

∴ 8 is a divisor of (4915−1) \left(49^{15}-1\right)