If Ruth began a job and worked continuously until she finished, at what time of day did she finish the job?

(1) She started the job at 8:15 a.m. and at noon of the same day she had worked exactly half of the time that it took her to do the whole job --> at noon of the same day, so after 3 hours and 45 minutes she started, Ruth had worked HALF OF THE TIME that it took her to do the whole job, which means that the total time it took Ruth to do the whole job is 7.5 hours, so she finished the job at 8:15 a.m+7.5 hours=15:45 p.m. Sufficient.

So as you can see we are not concerned about her rate at all.

(2) She was finished exactly 7.5 hours after she had started. Not sufficient, since we don't know at what time Ruth started the job.

Answer: A.
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Stmt 1 : The time taken from 8:15 a.m. to noon = 3 hrs 45 mins

Since this is half the time she took to complete the job,the total time taken by her to complete the job is = 6 hrs 90 mins i.e. 7 hrs 30 mins

This can help us arrive at the definite time she finished the job, hence this statement is sufficient.


Stmt 2 : While we know the total time she took to complete the job,we do not know the exact time she started working.

Since it is not possible for us to arrive at the exact time of completion,this statement is insufficient.

Answer : A

But what if she increased the rate at which she worked, then the time taken would be less. Thus we would not be able to calculate the time at which she finished

Still confused

We are told that 3 hours and 45 minutes is HALF OF THE TIME that it took her to do the whole job. If 3 hours and 45 minutes is half of the time then the total time it took Ruth to do the whole job is 7.5 hours.
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Answer will in this form: some time of the day.

To get that we need 2 things, start time and rate.

From 1, we get start time which is 8:15am and we are told that at 12 its half of the work so we can calculate when she finished. Don't waste your time on calculating the time. its not needed.

From 2, we know only know rate of work but no start time so numerous end time are possible. No sufficient.

ANSWER: A

Excuse me!
Can i ask you question?
at noon of the same day => is that 12pm?( why they did not write at 12 noon? ) i thought when they mention at noon it's a quite general. It can be 12h01pm.... 1pm, 2 pm ....til 6pm
So it makes my confusion when i cant have exact time that she finished HALF of THE TIME. Thus, we cant conclude it's sufficient
Thank you

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