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A qualified worker digs a well in 5 hours. He invites 2 appr [#permalink]
04 Oct 2006, 07:14

00:00

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Difficulty:

55% (medium)

Question Stats:

51% (02:57) correct
48% (02:07) wrong based on 128 sessions

A qualified worker digs a well in 5 hours. He invites 2 apprentices, both capable of working 3/4 as fast and 2 trainees both working 1/5 as fast as he. If the five-person team digs the same well, how much time does the team need to finish the job?

I must be totally blind! I do not see how you can get 1.4 hours out of 50/29.

Here's how I see it: each hour 29/50 of the job is completed, therefore after the first hour, 29/50 is complete and 21/50 is still remaining to be completed. 21/50 is just slightly less than 29/50, which is inline with the 1.7 that Juaz got.

I must be totally blind! I do not see how you can get 1.4 hours out of 50/29.

Here's how I see it: each hour 29/50 of the job is completed, therefore after the first hour, 29/50 is complete and 21/50 is still remaining to be completed. 21/50 is just slightly less than 29/50, which is inline with the 1.7 that Juaz got.

Thank you salr15! I am quite embarrassed, but you're right, the answers are a bit confusing... 1.4 to me means 1.4 hours, not 1 hr and 40 minutes. Thank you for the clarification!

Well, technically --- the question asks:
"how much time does the team need to finish the job?"

After the work calculation, we are left with 50/29 hours. This is equivalent to 1 hour and 21/29*60 minutes.

21/29 roughly yields "0.7241" which multiplied by 60 is roughly equivalent to 43.4 minutes.

Therefore, if we give the team 1:40 minutes, they will NOT be able to complete the job. --- Amongst the available choices, the team NEEDS 1:50 minutes to complete the job.

A qualified worker digs a well in 5 hours. He invites 2 appr [#permalink]
04 Oct 2013, 22:54

A qualified worker digs a well in 5 hours. He invites 2 apprentices, both capable of working 3/4 as fast and 2 trainees both working 1/5 as fast as he. If the five-person team digs the same well, how much time does the team need to finish the job? A 1:24 B 1:34 C 1:44 D 1:54 E 2:14
_________________

Re: A qualified worker digs a well in 5 hours. He invites 2 appr [#permalink]
05 Oct 2013, 01:36

Stiv wrote:

A qualified worker digs a well in 5 hours. He invites 2 apprentices, both capable of working 3/4 as fast and 2 trainees both working 1/5 as fast as he. If the five-person team digs the same well, how much time does the team need to finish the job? A 1:24 B 1:34 C 1:44 D 1:54 E 2:14

Your question sounds vague to me. The answer should be in terms of time. Anyway I just solved based on the data given.

Rate of the Work = 1 / 5

Rate of 2 apprentice = 2 * (1/5) * (3/4) = 6/20

Rate of 2 Trainees = 2 * (1/5) * (1/5) = 2/25

Total Rate of 5 people = (1/5) + (6/20) + (2/25) = 58/100

Time required to dig 1 Well = 1/ (58/100) = 100/58 hours _________________

I'm telling this because you don't get it. You think you get it which is not the same as actually getting it. Get it?

Work/rate problem - was my approach incorrect? [#permalink]
02 Nov 2013, 20:57

A qualified worker digs a well in 5 hours. He invites 2 apprentices, both capable of working 3/4 as fast and 2 trainees both working 1/5 as fast as he. If the five-person team digs the same well, how much time does the team need to finish the job?

A) 1:24 B) 1:34 C) 1:44 D) 1:54 E) 2:14

I started with the original rate for the worker as 1/5.

Each apprentice would have a rate (1/5)*(3/4) = 3/20

Each trainee would have a rate (1/5) * (1/5) = 1/25

Combining all of it together 1/5 + 3/20 + 3/20 + 1/25 + 1/25 = 58/100 per hour

After one hour, the remaining work to be done is 42/100

Is it possible to use this approach to solve the problem?

Re: Work/rate problem - was my approach incorrect? [#permalink]
03 Nov 2013, 03:30

undecidedonmba wrote:

A qualified worker digs a well in 5 hours. He invites 2 apprentices, both capable of working 3/4 as fast and 2 trainees both working 1/5 as fast as he. If the five-person team digs the same well, how much time does the team need to finish the job?

A) 1:24 B) 1:34 C) 1:44 D) 1:54 E) 2:14

I started with the original rate for the worker as 1/5.

Each apprentice would have a rate (1/5)*(3/4) = 3/20

Each trainee would have a rate (1/5) * (1/5) = 1/25

Combining all of it together 1/5 + 3/20 + 3/20 + 1/25 + 1/25 = 58/100 per hour

After one hour, the remaining work to be done is 42/100

Is it possible to use this approach to solve the problem?

Hi,

Your approach is perfectly correct but I do not see the answer options to be in sync with the question that's asked. The question is "hpw much time does the team need to finish the job" but answer options are in proportion/ratio format. Can you verify whether the question stem is correct? According to me the answer should be 50/29 hours. I used the same approach as yours.
_________________

Re: Work/rate problem - was my approach incorrect? [#permalink]
03 Nov 2013, 04:38

Expert's post

undecidedonmba wrote:

A qualified worker digs a well in 5 hours. He invites 2 apprentices, both capable of working 3/4 as fast and 2 trainees both working 1/5 as fast as he. If the five-person team digs the same well, how much time does the team need to finish the job?

A) 1:24 B) 1:34 C) 1:44 D) 1:54 E) 2:14

I started with the original rate for the worker as 1/5.

Each apprentice would have a rate (1/5)*(3/4) = 3/20

Each trainee would have a rate (1/5) * (1/5) = 1/25

Combining all of it together 1/5 + 3/20 + 3/20 + 1/25 + 1/25 = 58/100 per hour

After one hour, the remaining work to be done is 42/100

Is it possible to use this approach to solve the problem?