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Bill downloads the movie "Revenge of the Avengers" to his [#permalink]
27 Jul 2012, 17:11

00:00

A

B

C

D

E

Difficulty:

35% (medium)

Question Stats:

69% (03:26) correct
30% (02:28) wrong based on 105 sessions

Bill downloads the movie "Revenge of the Avengers" to his computer in 2.5 hours, using a download manager that downloads from 3 sources marked A, B and C. Each source provides download at a constant rate, but the rates of different sources are not necessarily identical. If the movie was downloaded from sources A and C alone, it would take 4 hours to complete the download. The next day, source B is available, but the other sources are inactive. How long will it take to download the trailer of the movie, a file that is 40 times smaller, from source B alone?

A. 6 hours and 40 minutes B. 15 minutes C. 12 minutes D. 10 minutes E. 3 minutes

Re: Bill downloads the movie "Revenge of the Avengers" to his [#permalink]
28 Jul 2012, 00:38

1

This post received KUDOS

Expert's post

superpus07 wrote:

Bill downloads the movie "Revenge of the Avengers" to his computer in 2.5 hours, using a download manager that downloads from 3 sources marked A, B and C. Each source provides download at a constant rate, but the rates of different sources are not necessarily identical. If the movie was downloaded from sources A and C alone, it would take 4 hours to complete the download. The next day, source B is available, but the other sources are inactive. How long will it take to download the trailer of the movie, a file that is 40 times smaller, from source B alone?

A. 6 hours and 40 minutes B. 15 minutes C. 12 minutes D. 10 minutes E. 3 minutes

Say the time needed to download the movie from source A alone be a minutes, from source B alone be b minutes, and from source C alone be c minutes. Next, since to download the movie from all three sources 2.5 hours (150 minutes) are needed then we have that:

\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=\frac{1}{150} (we can sum the rates to get the combined rate of 3 sources).

Also, since to download the movie from A and C alone 4 hours (240 minutes) are needed then we have that:

\frac{1}{a}+\frac{1}{c}=\frac{1}{240}.

Subtract the second equation from the first one: \frac{1}{b}=\frac{1}{150}-\frac{1}{240} --> \frac{1}{b}=\frac{1}{400} --> b=400.

So, to download the movie from source B alone 400 minutes are needed, therefore to download the trailer, which is 40 time smaller than the movies 400/40=10 minutes are needed.

Re: Bill downloads the movie "Revenge of the Avengers" to his [#permalink]
26 Dec 2013, 05:29

1

This post received KUDOS

superpus07 wrote:

Bill downloads the movie "Revenge of the Avengers" to his computer in 2.5 hours, using a download manager that downloads from 3 sources marked A, B and C. Each source provides download at a constant rate, but the rates of different sources are not necessarily identical. If the movie was downloaded from sources A and C alone, it would take 4 hours to complete the download. The next day, source B is available, but the other sources are inactive. How long will it take to download the trailer of the movie, a file that is 40 times smaller, from source B alone?

A. 6 hours and 40 minutes B. 15 minutes C. 12 minutes D. 10 minutes E. 3 minutes

Solution Here, please follow

1/A + 1/B + 1/C = 2/5 1/A + 1/C = 1/4

Then 1/B = 3/20

Time taken to download in B is 20/3. Now 40 times smaller then 20/3/40 = 20/120 = 1/6 hrs

Re: Bill downloads the movie "Revenge of the Avengers" to his [#permalink]
01 Feb 2014, 03:08

Hi Bunuel

I came down to 400 but wont answer. After ur explanation I am bit confused y u divide with 40...????

"So, to download the movie from source B alone 400 minutes are needed, therefore to download the trailer, which is 40 time smaller than the movies 400/40=10 minutes are needed".

Re: Bill downloads the movie "Revenge of the Avengers" to his [#permalink]
01 Feb 2014, 04:27

Expert's post

prasannajeet wrote:

Hi Bunuel

I came down to 400 but wont answer. After ur explanation I am bit confused y u divide with 40...????

"So, to download the movie from source B alone 400 minutes are needed, therefore to download the trailer, which is 40 time smaller than the movies 400/40=10 minutes are needed".

Rgds Prasannajeet

It should be very easy:

To download the movie you need 400 minutes. The trailer is 40 times smaller than the movies. Hoe many minutes do you need to download the trailer?
_________________

Re: Bill downloads the movie "Revenge of the Avengers" to his [#permalink]
01 Feb 2014, 19:19

Let the movie size be 400 u. Given,A+C=4 hrs. A+C=100 u/hr And A+B+C=2.5 hrs or 400/2.5=160 u/hr B alone=160-100=60 u/hr Trailer=40 times smaller or400/40=10 u B will take 10/60 hrs or 10 minutes. Ans D