Let E be the set of all integers whose unit (ones) digit is 1. If a number is chosen uniformly at random from {2, 3, 4, …, 50}, what is the probability it belongs to E?

Introduction / Context:This question checks counting with simple modular (last-digit) patterns over a finite range. We pick uniformly from consecutive integers and count those ending with 1.

Given Data / Assumptions:

• Set S = {2, 3, 4, …, 50} has 49 numbers.
• Event E: unit digit = 1.

Concept / Approach:

• Within any block of ten consecutive integers, exactly one ends with digit 1.
• Enumerate within the given finite range.

Step-by-Step Solution:

Verification / Alternative check:Check endpoints: 1 is not included; 51 is outside the range; thus exactly four hits (every ten steps) remain: 11, 21, 31, 41.

Why Other Options Are Wrong:

• 5/49, 3/49, 2/49 miscount how many candidates end with 1.
• “None of these” is false because 4/49 is attainable.

Common Pitfalls:

• Accidentally including 1 or 51 which are outside the closed interval.

Final Answer:4/49