Question

The lifetime of super Tires is approximately normally distributed, with a mean of $40,000miles$ and a standard deviation of $2,500miles$ under normal driving conditions.

Answer 1

Given,

$\mu =40,000,\sigma =2500$

$z=\frac{x-\mu }{\sigma }$

$1=\frac{x-40000}{2500}$

$2500=x-40000$

$\Rightarrow x=42,500$

Therefore the lifetime of super tires is 42,500 miles.