It is currently 14 Dec 2018, 01:59

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# To service a single device in 12 seconds, 700 nanorobots are

Author Message
TAGS:
GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4749
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 93

Kudos [?]: 1659 [0], given: 396

To service a single device in 12 seconds, 700 nanorobots are [#permalink]  18 Jun 2018, 14:51
Expert's post
00:00

Question Stats:

77% (02:21) correct 22% (02:11) wrong based on 9 sessions
To service a single device in 12 seconds, 700 nanorobots are required, with all nanorobots
working at the same constant rate. How many hours would it take for a single nanorobot to service
12 devices?
(A) $$\frac{7}{3}$$
(B) 28
(C) 108
(D) 1,008
(E) 1,680
[Reveal] Spoiler: OA

_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Director
Joined: 20 Apr 2016
Posts: 758
Followers: 6

Kudos [?]: 514 [0], given: 94

Re: To service a single device in 12 seconds, 700 nanorobots are [#permalink]  28 Jun 2018, 17:09
sandy wrote:
To service a single device in 12 seconds, 700 nanorobots are required, with all nanorobots
working at the same constant rate. How many hours would it take for a single nanorobot to service
12 devices?
(A) $$\frac{7}{3}$$
(B) 28
(C) 108
(D) 1,008
(E) 1,680

We know

Work = Rate * Time * No. of individual

In first to need to find out the rate

Given time = 12 seconds , No. of Individual = 700 nanorobots and Work = 1

Therefore; 1 = Rate * 12 * 700

or Rate = $$\frac{1}{8400}$$

Now for the second part we have

Work = 12 device, No. of Individual = 1 nanorobots and Rate = $$\frac{1}{8400}$$

Therefore; $$12 =$$ $$\frac{1}{8400} * 1 * Time$$

or Time = 12 * 8400 = 100800 seconds = $$\frac{100800}{3600}$$hour = 28 hours
_________________

If you found this post useful, please let me know by pressing the Kudos Button

GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4749
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 93

Kudos [?]: 1659 [0], given: 396

Re: To service a single device in 12 seconds, 700 nanorobots are [#permalink]  10 Jul 2018, 05:24
Expert's post
Explanation

To solve a Rates & Work problem with multiple workers, modify the standard formula Work = Rate × Time to this:

Work = Individual Rate × Number of Workers × Time

Solve for an individual nanorobot’s rate, using the fact that 700 nanorobots can service 1 device in 12 seconds. Notice that the “work” here is 1 device:

Work = Individual Rate × Number of Workers × Time

1 device = (R)(700)(12 seconds)

R = $$\frac{1}{8400}$$ devices per second.

That is, each nanorobot can service $$\frac{1}{8400}$$ of a device in 1 second. Plug that rate back into the formula, but using the details from the second sentence in the problem:

Work = Individual Rate × Number of Workers × Time

12 devices = ($$\frac{1}{8400}$$ devices per second)(1)(T)
T = 100,800 seconds

The answer is 100,800 seconds. Divide by 60 to convert this time to 1,680 minutes; divide by 60 again to get 28 hours.
_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Re: To service a single device in 12 seconds, 700 nanorobots are   [#permalink] 10 Jul 2018, 05:24
Display posts from previous: Sort by

# To service a single device in 12 seconds, 700 nanorobots are

 Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.