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07 Oct 2014, 08:55
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D
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Difficulty:
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81% (00:56) correct
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Tough and Tricky questions: Ratios
Joe, Bob and Dan worked in the ratio of 1:2:4 hours, respectively. How many hours did Bob work?
(1) Together, Joe, Bob and Dan worked a total of 49 hours.
(2) Dan worked 21 hours more than Joe
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
07 Oct 2014, 09:05
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ok, so knowing the ratio for each person, we can rewrite as x:2x:4x, where X is a factor, and the total time they worked can be written as the sum of x, 2x, and 4x. Therefore, in order to find the answer to our question, we need to find out either total hours worked, or X.
(1) tells us the total number of hours worked by Joe, Bob and Dan. Thus, we can solve for X.
49 = 7x
x = 49/7
x = 7
Bob worked 2x => he worked 7*2 = 14 h. sufficient.
(2) Dan worked 21 hours more than Joe. We can rewrite this as 4x - x = 21. From this, we can solve for X.
3x = 21
x = 7
Bob worked 7*2 = 14 h. sufficient.
Of course, for DS, we do not need to do all the calculations, just to check if we can solve for X or not.
(1) tells us the total number of hours worked by Joe, Bob and Dan. Thus, we can solve for X.
49 = 7x
x = 49/7
x = 7
Bob worked 2x => he worked 7*2 = 14 h. sufficient.
(2) Dan worked 21 hours more than Joe. We can rewrite this as 4x - x = 21. From this, we can solve for X.
3x = 21
x = 7
Bob worked 7*2 = 14 h. sufficient.
Of course, for DS, we do not need to do all the calculations, just to check if we can solve for X or not.
07 Oct 2014, 09:44
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Bunuel
That was a sitter -
Ratio = 1: 2: 4 = X : 2X : 4X
1 - Total work by J B and D = 49 hrs. = we can calculate the number of hours each worked
2 - D worked 21 hours more than J = 4X - X = 21 - This will also give the value of B's work
Ans - D
