SOLUTION: Overall, the amount of work-hours involved in the festival preparation is normally distributed around 80 hours with a standard deviation of 8 hours. a) What�s the probability th

Question 624633: Overall, the amount of work-hours involved in the festival preparation is normally distributed around 80 hours with a standard deviation of 8 hours.
a) What�s the probability that the mean number of work-hours will be between 85 and 90?
b) The members at or below the 10%ile of number of worked-hours must attend a one-on-one meeting with their supervisor. At least how many work-hours you should have in order to avoid attending such session?
c) How likely (what is the probability) is it to have the number of involved work-hours below 80?
d) How likely (what is the probability) is it to have the number of involved work-hours below 65?
e) How likely (what is the probability) is it that some employee will have his/her involved work- hours between 73 and 88?

Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!

 

Hi,

I. Recommend understanding how to derive z-score  and it's corresponding 

Probability (using Excel function NORMSDIST(z)) of data being to the left of x value given

II. Understanding the Standard Normal Curve in terms of z-scores:

Important to Understand z -values as they relate to the Standard Normal curve:

Below:  z = 0, z = � 1, z= �2 , z= �3 are plotted.  

Note: z = 0 (x equal to the mean) 50% of the area under the curve is to the left and %50 to the right



III. then, unless You have a Calculator You know how to use:

would recommend using a site such as the following to check Your work:

easycalculation.com/statistics/normal-distribution.php 

RELATED QUESTIONS

The amount of work-hours involved in the festival preparation by company employees is... (answered by SadieKhan)
The amount of time that office workers at Company XYZ spend on the computer each workday... (answered by ewatrrr)
The lifetimes of light bulbs of a particular type are normally distributed with a mean of  (answered by Boreal)
Imagine that the number of hours one works per week is normally distributed, with an mean  (answered by Theo)
College students average 7 hours of sleep per night with a standard deviation of 40... (answered by stanbon)
College students average 8.7 hours of sleep per night with a standard deviation of 40... (answered by stanbon)
The amount of time that Carlos plays video games in any given week is normally... (answered by ewatrrr)
The lifetime of ZZZ batteries is normally distributed with a mean of 270 hours and a... (answered by stanbon)
The sick-leave time of employees in a firm in a month is normally distributed with a mean  (answered by Boreal)