Question

13. A data set has a mean of x=3905 and a standard deviation of 110. Find the z-score for each of the following.

14. A random sample of 80 tires showed that the mean mileage per tire was 41,400mi, with a standard deviation of 4700mi.

Answer 1

Question 13

Part (a)

`(3840-3905)/(110)=\boxed{0.5\overline{90}}`

By similar logic, the other answers are

(b) 2.6818181....

(c) 3.5909090...

(d) 1.1363636...

Question 14

Part (a)

`(46800-41400)/(4700) \approx \boxed{1.15}`

Part (b)

`-2.57=(x-41400)/(4700) \\ \\ -2.57(4700)=x-41400 \\ \\ x=41400-2.57(4700) \\ \\ x \approx \boxed{29300}`