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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # Jenny takes 3 hours to sand a picnic table; Laila can do the  Question banks Downloads My Bookmarks Reviews Important topics
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Retired Moderator Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 175

Kudos [?]: 3037 , given: 394

Jenny takes 3 hours to sand a picnic table; Laila can do the [#permalink]
Expert's post 00:00

Question Stats: 96% (00:51) correct 3% (00:00) wrong based on 28 sessions
Jenny takes 3 hours to sand a picnic table; Laila can do the same job in $$\frac{1}{2}$$ hour. Working together at their respective constant rates, Jenny and Laila can sand a picnic table in how many hours?

(A) $$\frac{1}{6}$$
(B) $$\frac{2}{9}$$
(C) $$\frac{1}{3}$$
(D) $$\frac{3}{7}$$
(E) $$\frac{5}{6}$$
[Reveal] Spoiler: OA

_________________

Sandy
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Try our free Online GRE Test Active Member Joined: 29 May 2018
Posts: 126
Followers: 0

Kudos [?]: 112  , given: 4

Re: Jenny takes 3 hours to sand a picnic table; Laila can do the [#permalink]
1
KUDOS
sandy wrote:
Jenny takes 3 hours to sand a picnic table; Laila can do the same job in $$\frac{1}{2}$$ hour. Working together at their respective constant rates, Jenny and Laila can sand a picnic table in how many hours?

(A) $$\frac{1}{6}$$
(B) $$\frac{2}{9}$$
(C) $$\frac{1}{3}$$
(D) $$\frac{3}{7}$$
(E) $$\frac{5}{6}$$

Part of 1 hour work by Jenny = 1/3

Part of 1 hour work by Laila = 1 / 1/2 = 2.

Now part of 1 hour work by both = 1/3 + 2 = 7/3.

Now time inversely prop to work =? 3/7.
Retired Moderator Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 175

Kudos [?]: 3037 , given: 394

Re: Jenny takes 3 hours to sand a picnic table; Laila can do the [#permalink]
Expert's post
Explanation

Since the two women are working together, add their rates. To find their individual rates, divide work by time. Never divide time by work! (Also, be careful when dividing the work by $$\frac{1}{2}$$.

The rate is the reciprocal of $$\frac{1}{2}$$, or 2 tables per hour.)

Find Jenny and Laila’s combined rate, then divide the work required (1 table) by this rate: 1 table ÷ $$\frac{7}{3}$$ table per hour = $$\frac{3}{7}$$ hour.

Attachment: image1.jpg [ 60.76 KiB | Viewed 1612 times ]

Hence option D is correct!
_________________

Sandy
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Try our free Online GRE Test Re: Jenny takes 3 hours to sand a picnic table; Laila can do the   [#permalink] 10 Jul 2018, 05:41
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