If John and Jack collaborate, they can produc… | GMAT Sprint

Free Practice Question

PS · Problem Solving

555-605

Work Rate Problems

If John and Jack collaborate, they can produce 30 pages in one hour. Should Jack enhance his typing speed by 60%, they would manage to produce 36 pages in the same time. What is the ratio of Jack's regular typing speed to John's?

Correct answer marked below

1/4

1/3

1/2

Correct

3/5

2/3

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Explanation

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Official Explanation

Official

Let John's typing speed be

x

pages per hour and Jack's be

y

pages per hour. Together, their combined rate gives us the equation:

(x+y)*1=30

which simplifies to

x+y=30

. If Jack increases his speed by 60%, they can type 36 pages in one hour, leading to the equation:

(x+1.6y)*1=36

which simplifies to…

Comments

PratyushApr 17, 2024

thanks for the answer

What this question tests

Your ability to combine individual work rates, usually by working with the fraction of a job completed per unit of time.

Adding the times instead of the rates, or forgetting to take the reciprocal when combining rates.