Question:medium

Arun selected an integer \( x \) between 2 and 40, both inclusive. He noticed that the greatest common divisor of the selected integer \( x \) and any other integer between 2 and 40, both inclusive, is 1. How many different choices for such an \( x \) are possible?

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Integers that are coprime with all others are usually prime numbers, as they have no divisors other than 1.
Updated On: Nov 26, 2025
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The Correct Option is B

Solution and Explanation

Step 1: Problem Definition.
Determine the count of integers within the range [2, 40] that are relatively prime to all other integers in the same range.
Step 2: Identify Coprime Numbers.
A number is considered coprime with all others in a set if its greatest common divisor (GCD) with each of those other numbers is 1. We must count how many such numbers exist.
Step 3: Solution Derivation.
The count is 8. This is because the prime numbers in the range [2, 40] satisfy the condition.
Final Answer: \[\boxed{8}\]
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