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You may need to use the appropriate appendix table to answer this question. The time needed to complete a final examination in a particular college course is normally distributed with a mean of 80 minutes and a standard deviation of 10 minutes. Answer the following questions. (a) What is the probability of completing the exam in one hour or less

User Esteban PS
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Answer:

The probability of completing the exam in one hour or less is 0.0228.

Explanation:

Given: Mean = 80

Standard deviation = 10

To find: The probability of completing the exam in one hour or less.

We have,
\mu=80 and
\sigma=10.

Now, the z-value is the sample mean decreased by the population mean divided by the standard deviation.


z=\frac{\bar{x}-\mu}{\sigma}


z=(60-80)/(10)


z=-2

Now,
z=\frac{\bar{x}-\mu}{\sigma}


z=(75-80)/(10)


z=-0.5

Again,
z=\frac{\bar{x}-\mu}{\sigma}


z=(90-80)/(10)


z=1

Using appropriate appendix table, we get
P(z<-2)=0.0228.

User Lateralus
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