Earl can stuff advertising circulars into envelopes at the rate of 45 envelopes per minute and Ellen requires a minute and a half to stuff the same number of envelopes. Working together, how long will it take Earl and Ellen to stuff 300 envelopes?

Correct answer marked below

15 minutes

4 minutes

Correct

3 minutes 30 seconds

3 minutes 20 seconds

2 minutes

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Explanation

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Comments

ClelioMay 2

Wait, Ellen does 45 envelopes in 1.5 min? So that's 30 per minute, right? Then together 75 per minute, and 300/75 = 4. Got it, B.

EmilyMay 12

Yep, 30/min for Ellen. This one's pretty straightforward once you get the rates straight.

JonasMay 13

Classic trap. Always double check the units before combining rates.

VeidesApr 30

This is on the easier side but I still managed to mess up the first time by adding the times instead of the rates lol

PrathyooshMay 9

Haha been there. You can't add times when working together, only rates.

ShantanuSep 22

Earl: 45/min. Ellen: 45/1.5 = 30/min. Combined 75/min. 300/75 = 4 min. Answer B.

SrikanthSep 27

Nice clean breakdown. Took me a sec to see Ellen's rate is just 2/3 of Earl's.

HarshMay 3

Is this really 505-555? Felt more like a 400-level question to me. Either way, B.

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.