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A class has 136 students. The time it takes to grade one exam paper is on...

A class has 136 students. The time it takes to grade one exam paper is on average 3 minutes and has

standard deviation 90 seconds. Estimate the probability that it will take less than 7 hours for one

person to grade all of the exams.

math   Statistics-And-Probability   
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Answer #1

The probability that it will take less than 7 hours for one person to grade all of the exams

.............................................90 seconds = 1.5 minute

=P[Z<2.67]

=0.9962...........................by using normal probability table or Excel command =NORMSDIST(2.67)

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