Two chefs, Chef Andrew and Chef Bonnie, were hired to prepare a dinner

Question

Two chefs, Chef Andrew and Chef Bonnie, were hired to prepare a dinner. The two chefs began working at the same time, but Chef Andrew was only able to work for 2 hours. How many hours did it take Chef Bonnie, working alone, to finish making the dinner?

(1) Working alone, Chef Andrew made 1/4 of the meal.

(2) It would have taken 6 hours for Chef Bonnie to cook the entire meal herself.

(1) Working alone, Chef Andrew made 1/4 of the meal.

(2) It would have taken 6 hours for Chef Bonnie to cook the entire meal herself.

Bunuel · Accepted Answer

Two chefs, Chef Andrew and Chef Bonnie, were hired to prepare a dinner. The two chefs began working at the same time, but Chef Andrew was only able to work for 2 hours. How many hours did it take Chef Bonnie, working alone, to finish making the dinner?

(1) Working alone, Chef Andrew made 1/4 of the meal.

(2) It would have taken 6 hours for Chef Bonnie to cook the entire meal herself.

(1) Working alone, Chef Andrew made 1/4 of the meal. So, Andrew made 1/4 of the meal in 2 hours, which means that he needs 8 hours to cook the entire meal himself. Plus, since he made 1/4 of the meal, then the remaining 3/4 was made by Bonnie. We don't know the rate of Bonnie. Not sufficient.

(2) It would have taken 6 hours for Chef Bonnie to cook the entire meal herself. We know the rate of Bonnie, but don't know what part of the job was done by her. Not sufficient.

(1)+(2) Bonnie to cook the entire meal herself needs 6 hours and she made 3/4 of the meal, thus she spent total of 6*3/4 = 4.5 hours on that. Therefore to finish making the dinner it took her 4.5 - 2 = 2.5 hours. Sufficient.

Answer: C.

Actually there was no need to calculate anything, because when we combine the statements we know everything: both rates and part of the job done by Andrew.

anupamadw · Answer

Hi Bunuel

Ccould you please clarify one thing?
It is given that both chefs started working together, so do we have to consider work done by Bonnie in 2 hrs?

Thanks
Anupama

agf625 · Answer

I think it's irrelevant whether or not we include the two hours working side by side... either way we know enough information to calculate it.

KrishnakumarKA1 · Answer

Statement analysis
St 1: Andrew did 1/4 of work. That means Bonnie did 3/4 of the work. but we have no idea about the rate of work done by bonnie. Hence the time taken cannot be calculated. INSUFFICIENT.

St 2: according to statement, rate of work for Bonnie is 1/6 work/per hour. But we have no idea about wt aportion of work was completed by Andrew. INSUFFICIENT

St 1 & St2: now we have amount of work done by bonnie i.e. 3/4 and rate at which he cooks i.e. 1/6. 
Therefore, the time taken to complete the rest of the work is (3/4)/(1/6) - 2 = 4.5 hours. ANSWER

Option C

elainetianfong · Answer

Hi.
I also have another explanation.

1. I understand this wording as "working together, chef Andrew alone contributed to 1/4 of the work done"
By this mean, chef Bonnie made up the rest 3/4.
So, we can conclude the working rate of A/B is 1/3

2. It takes 6 hrs for chef Bonnie to finish work alone => not suff.

(1+2) => we can deduce that chef Andrew would take 3x6 = 18 hours to finish work alone. 
So, together they should need only (1/18 + 1/6)= 4.5 hours to get things done.
However, as chef Andrew left only after 2 hrs, so there is (1 - 2/4.5) = 5/9 work not yet finished. 
So, chef Bonnie would cover 5/9 work in (5/9)x(6)=10/3 hours.
So, C is the answer.

Posted from my mobile device

GMATinsight · Answer

Answer: Option C

Please check the video for the step-by-step solution.

GMATinsight's Solution

https://www.youtube.com/watch?v=psAVIIA_KpY

Tonkotsu · Answer

Two chefs, Chef Andrew and Chef Bonnie, were hired to prepare a dinner. The two chefs began working at the same time, but Chef Andrew was only able to work for 2 hours. How many hours did it take Chef Bonnie, working alone, to finish making the dinner?

(1) Working alone, Chef Andrew made 1/4 of the meal.

(2) It would have taken 6 hours for Chef Bonnie to cook the entire meal herself.

Algebraically, I'd position the problem like below:

1_{job}= (\frac{1_{job}}{A_{hours}} + \frac{1_{job}}{B_{hours}})*2_{hours} + \frac{1_{job}}{B_{hours}}x_{hours}

We have three unknowns A, B, and X. Goal is to find X.

(1) Working alone, Chef Andrew made 1/4 of the meal.

Tells us what A would be, but will not help us find X without B.  insufficient

(2) It would have taken 6 hours for Chef Bonnie to cook the entire meal herself.

Tells us what B would be, but will not help us find X without A.  insufficient

(1) & (2)

Tells us what A and B both are, to find X.  sufficient

bumpbot · Answer

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Two chefs, Chef Andrew and Chef Bonnie, were hired to prepare a dinner

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