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2008 AMC 12A Problems/Problem 1

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The following problem is from both the 2008 AMC 12A #1 and 2008 AMC 10A #1, so both problems redirect to this page.

Problem

A bakery owner turns on his doughnut machine at \text{8:30}\ {\small\text{AM}}. At \text{11:10}\ {\small\text{AM}} the machine has completed one third of the day's job. At what time will the doughnut machine complete the job?

\mathrm{(A)}\ \text{1:50}\ {\small\text{PM}}\qquad\mathrm{(B)}\ \text{3:00}\ {\small\text{PM}}\qquad\mathrm{(C)}\ \text{3:30}...

Solution

The machine completes one-third of the job in \text{11:10}-\text{8:30}=\text{2:40} hours. Thus, the entire job is completed in 3\cdot(\text{2:40})=\text{8:00} hours.

Since the machine was started at \text{8:30 AM}, the job will be finished 8 hours later, at \text{4:30 PM}. The answer is \mathrm{(D)}.

See Also

2008 AMC 12A (ProblemsResources)
Preceded by
First Question
Followed by
Problem 2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
2008 AMC 10A (ProblemsResources)
Preceded by
First Question
Followed by
Problem 2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Looking for a challenging geometry text? Preparing for MATHCOUNTS or the AMC exams? Check out Art of Problem Solving's Introduction to Geometry by Richard Rusczyk.
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