Download The_Normal_Distribution skills practice

NAME _____________________________________________ DATE ____________________________ PERIOD _____________
Skills Practice
The Normal Distribution
A normal distribution has a mean of 287 and a standard deviation of 65.
1. What range of values represents the middle 68% of the data?
2. What percent of data will be more than 417?
3. What range of values represents the low 0.15% of the data?
Find the missing variable. Indicate the position of X in the distribution.
4. z if μ = 67, X = 81, and σ = 11.3
5. z if μ = 19.1, X = 15.9, and σ = 3.7
6. X if z = –1.34, μ = 81.1, and σ = 6.6
7. σ if μ = 29.4, X = 19.3, and z = –2.13
8. DELIVERY The time it takes a bicycle courier to deliver a parcel to his farthest customer is normally distributed with
a mean of 38.6 minutes and a standard deviation of 4.7 minutes.
a. About what percent of the courier’s trips to this customer take between 35 and 40 minutes?
b. About what percent of the courier’s trips to this customer take between 40 and 45 minutes?
c. About what percent of the courier’s trips to this customer take less than 30 minutes?
9. TESTING The average time it takes sophomores to complete a math test is normally distributed with a mean of
63.3 minutes and a standard deviation of 12.3 minutes.
a. About what percent of the sophomores take more than 80 minutes to complete the test?
b. About what percent of the sophomores take between 50 and 60 minutes?
c. About what percent of the sophomores take less than 40 minutes to complete the test?
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