A marzipan factory has two machines producing marzipan.

[BTGmoderatorLU]

A marzipan factory has two machines producing marzipan. Every day, the two machines operate constantly from 08:00 to 18:00, and produce together N kg of marzipan. What percent of the total amount of marzipan produced by machines W and D together was produced by machine W?

1) Working alone, it takes machine W twenty-five hours to produce (N/2) kg of marzipan.
2) Machine W alone produces (N/2) kg of marzipan in double the time it takes machine D alone to produce N kg of marzipan.

The OA is D.

(2) Machine W alone produces (N/2) kg of marzipan in double the time it takes machine D alone to produce N kg of marzipan.

How is option B sufficient? it doesn't state anything about the time for either machine W or machine D; it only compares the work of two machines.

I feel the answer should be A. Thanks!

[Jay@ManhattanReview]

A marzipan factory has two machines producing marzipan. Every day, the two machines operate constantly from 08:00 to 18:00, and produce together N kg of marzipan. What percent of the total amount of marzipan produced by machines W and D together was produced by machine W?

1) Working alone, it takes machine W twenty-five hours to produce (N/2) kg of marzipan.
2) Machine W alone produces (N/2) kg of marzipan in double the time it takes machine D alone to produce N kg of marzipan.

The OA is D.

(2) Machine W alone produces (N/2) kg of marzipan in double the time it takes machine D alone to produce N kg of marzipan.

How is option B sufficient? it doesn't state anything about the time for either machine W or machine D; it only compares the work of two machines.

I feel the answer should be A. Thanks!

Statement 2 is sufficient since the ratio of the rates of machine W and D can be known. With this information, the ratio of their output can be known.

Say machine D takes x hours to produce N kg of marzipan; thus, machine W would take (2x)*2 = 4x hours to produce N kg of marzipan.

The ratio of time taken -- W : D :: 1 : 4. Thus, we can calculate the percent of the total amount of marzipan produced by machines W and D together was produced by machine W. Sufficient.

The correct answer: D

Hope this helps!

-Jay
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[GMATGuruNY]

2) Machine W alone produces (N/2) kg of marzipan in double the time it takes machine D alone to produce N kg of marzipan.

How is option B sufficient? it doesn't state anything about the time for either machine W or machine D; it only compares the work of two machines.

Let N = 4 kg and D's time for N kg = 1 hour.
Thus, D's rate = (4 kg)/(1 hour) = 4 kg per hour.

Since W produces N/2 kg (2 kg) in twice D's time for N kg (2 hours), W's rate = (2 kg)/(2 hours) = 1 kg per hour.

Combined rate for D+W = 4+1 = 5 kg per hour.
Of every 5 kg produced each hour when D and W work together, D will produce 4 kg and W will produce 1 kg.
Thus:
(W's hourly work)/(total hourly work) = 1/5 = 20%.
SUFFICIENT.