In: Statistics and Probability
µ = 15
sd = 8
a)
= P(-0.38 < Z < 0.5)
= P(Z < 0.5) - P(Z < -0.38)
= 0.6915 - 0.3520
= 0.3395
b)
= P(Z > 1.63) + P(Z < -1.25)
= 1 - P(Z < 1.63) + P(Z < -1.25)
= 1 - 0.9484 + 0.1056
= 0.1572
Since the probability not less than 0.05, it is not unusual.
Th proportion is 0.1572