Mary wraps 5 parcels in 2 minutes while Kerry unwraps a parcel every ten minutes. If both work together how long will it take them to have 120 wrapped parcels ready?

A) 5 mins

B) 10 mins

C) 20 mins

D) 35 mins

E) 50 mins

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- Jul 8th 2013, 10:59 AMusre123Work rate problem
Mary wraps 5 parcels in 2 minutes while Kerry unwraps a parcel every ten minutes. If both work together how long will it take them to have 120 wrapped parcels ready?

A) 5 mins

B) 10 mins

C) 20 mins

D) 35 mins

E) 50 mins - Jul 8th 2013, 11:14 AMearbothRe: Work rate problem
Hello,

let x denote the number of minutes it takes to get the 120 Parcels.

You know that Mary wraps $\displaystyle \frac52 \frac{parcels}{min}$

and Kerry unwraps $\displaystyle \frac1{10} \frac{parcels}{min}$

That means the number of parcels is determined by:

$\displaystyle \frac52 \frac{parcels}{min} \cdot x \ min - \frac1{10} \frac{parcels}{min} \cdot x \ min = 120 \ parcels$

Solve for x. - Jul 8th 2013, 05:53 PMusre123Re: Work rate problem
Hey, its ok, I got it. Thanks a lot. It was really easy. Mary does 5/2= 2.5 boxes/minute. Kerry unwraps 1/10= 0.1 per minute. So Mary - Kerry (since they're doing opposite things) is equal to 2.4. Now 2.4 * 120= 50 minutes.

- Jul 8th 2013, 10:03 PMearbothRe: Work rate problem