Source: Manhattan Prep
Bob works exactly 8 hours per day assembling widgets at a constant rate. How many widgets can he assemble in half of a workday?
1) Bob produces 20 widgets in a full workday.
2) Bob produces 50 widgets in 20 hours.
The OA is D
Bob works exactly 8 hours per day assembling widgets at a
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If we want to know how many widgets Bob assembles in 4 hours, we need to know his constant RATE of widget assembly.
1) Bob produces 20 widgets in a full workday.
We know that a full workday is 8 hours, so this is sufficient to tell us that his rate is 2.5 widgets per hour.
Or, you can infer that if he makes 20 widgets in a full day, he'll make 10 in half a day. Sufficient.
2) Bob produces 50 widgets in 20 hours.
If we have an output in a given amount of time, this is sufficient to tell us his rate - you don't even need to calculate. If you did, though:
50/20 = 5/2 = 2.5 widgets per hour. We can easily use this to calculate how many widgets in 4 hours: (2.5)(4) = 10.
Or again, you can divide: 20 hours is 5 times as long as 4 hours, so he'll produce 5 times as much. 50/5 = 10 in 4 hours.
The answer is D.
1) Bob produces 20 widgets in a full workday.
We know that a full workday is 8 hours, so this is sufficient to tell us that his rate is 2.5 widgets per hour.
Or, you can infer that if he makes 20 widgets in a full day, he'll make 10 in half a day. Sufficient.
2) Bob produces 50 widgets in 20 hours.
If we have an output in a given amount of time, this is sufficient to tell us his rate - you don't even need to calculate. If you did, though:
50/20 = 5/2 = 2.5 widgets per hour. We can easily use this to calculate how many widgets in 4 hours: (2.5)(4) = 10.
Or again, you can divide: 20 hours is 5 times as long as 4 hours, so he'll produce 5 times as much. 50/5 = 10 in 4 hours.
The answer is D.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
EdM in Mind, Brain, and Education
Harvard Graduate School of Education