A number is selected at random from the first… | GMAT Sprint

Free Practice Question

PS · Problem Solving

sub-505

Divisibility/Multiples/Factors

A number is selected at random from the first 120 positive integers. What is the probability that it is a multiple of 4?

Answer Choices

Correct answer marked below

29/120

40/120

1/4

Correct

31/120

2/3

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Explanation

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Official Explanation

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A number is selected at random from the first 120 positive integers. We need to find the probability that it is a multiple of 4. Using the formula: 1 + [ {last multiple of increment in the given range - first multiple of the increment in the…

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Comments

AshNov 24, 2024

Thanks for sharingThank you for sharing!!thanks for sharing

OjasMay 2, 2025

Great!

NainikaAug 18

Wait is it just 30/120? Because 4×30=120 so there are 30 multiples. That's 1/4 right?

ElleAug 20

thanks, got it now

VeidesSep 21

How did people get 31/120? Is 120 itself not counted or something?

NiklasOct 5

ohh so it's like double counting. thanks!

PranavSep 7

finally one I can actually get right lol

RitikaApr 20

I keep messing these up. Tip for everyone: just divide the range by the divisor, don't try to list them out. saved me.

What this question tests

What it tests

Your understanding of divisibility rules, least common multiples, and greatest common factors.

Common trap

Forgetting that 1 is not prime and that every integer divides 0.