Let T = the distance, in miles, a tire lasts
T ~ N(70000,4400<span>²</span>)
P(T
75000)
= P(Z
)
= P(Z
)
≈ P(Z 1.14)
= 1 - P(Z < 1.14)
≈ 1 - 0.8729
= 0.1271
T ~ N(70000,4400<span>²</span>)
P(T
= P(Z
= P(Z
≈ P(Z
= 1 - P(Z < 1.14)
≈ 1 - 0.8729
= 0.1271