Question

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 14

Part (a)

$\frac{46800-41400}{4700} \approx \boxed{1.15}$

Part (b)

$-2.57=\frac{x-41400}{4700} \\ \\ -2.57(4700)=x-41400 \\ \\ x=41400-2.57(4700) \\ \\ x \approx \boxed{29300}$