Correct Answer: Option C

Explanation

\(402_y = 102_ten\)

⇒ 4 x y\(^2\) + 0 x y\(^1\) + 2 x y\(^0\) = 102

⇒ 4y\(^2\) + 0 + 2 x 1 = 102

⇒ 4y\(^2\) + 2 = 102

⇒ 4y\(^2\) = 102 - 2

⇒ 4y\(^2\) = 100

⇒ y\(^2 = \frac {100}{4}\)

⇒ y\(^2\) = 25

∴ y = √25 = 5

There is an explanation video available below.

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