SOLUTION: Question It has been found that the times taken by people to complete the income tax form follows a Normal distribution with a mean of 100 minutes and a standard deviation of 20 m

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Question 1058438: Question
It has been found that the times taken by people to complete the income tax form follows a Normal distribution with a mean of 100 minutes and a standard deviation of 20 minutes.
Calculate the following probabilities:
1. A person takes 110 minutes or more to complete the form
2. A person takes between 100 and 125 minutes to complete the form
3. A person takes between 75 and 115 minutes to complete the form
4. A person takes less than 120 minutes to complete the form
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Calculate a z score for each case. I'll do one you do the others.
1.z=%28110-100%29%2F20=10%2F20=1%2F2
P%28x%3E110%29=P%28z%3E1%2F2%29=1-P%28z%3C=1%2F2%29=1-0.691462=0.309
2.P=P%28x%3C=125%29-P%28x%3C=100%29=P%28x%3C=125%29-0.5
3.P=P%28x%3C=115%29-P%28x%3C=75%29
4.P=P%28x%3C=120%29