Question

A college placement office conducted a survey of 100 engineers who had graduated from Stanford University. For these engineers, the mean salary was computed to be $72,000 with a standard deviation of $22,000. The distribution of salary is roughly bell-shaped. a) What percentage of these engineers will earn between $55,040 and $88,960? b) What is the probability that the average income of 4 engineers will be between $55,040 and $88,960? c) What would be the 90th percentile for the income of these individual engineers? d) What would be the 90th percentile for the average income of groups of 9 engineers? e) Why is the 90th percentile in (d) a smaller number than the value in (c)? Explain using the bell curve and what happens to it when you are looking at the average of a group.

          A college placement office conducted a survey of 100 engineers who had graduated from Stanford University. For these engineers, the mean salary was computed to be $72,000 with a standard deviation of $22,000. The distribution of salary is roughly bell-shaped.

a) What percentage of these engineers will earn between $55,040 and $88,960?
b) What is the probability that the average income of 4 engineers will be between $55,040 and $88,960?
c) What would be the 90th percentile for the income of these individual engineers?
d) What would be the 90th percentile for the average income of groups of 9 engineers?
e) Why is the 90th percentile in (d) a smaller number than the value in (c)? Explain using the bell curve and what happens to it when you are looking at the average of a group.

Added by Angela L.

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