Answer:
1) 0.99348
2) 0.55668
Step-by-step explanation:
Assume that men’s weights are normally distributed with a mean given by = 172lb and a standard deviation given by =29lb. Using the Central Limit Theorem to solve the following exercises
When given a random number of samples, we use the z score formula:
z-score is z = (x-μ)/σ/√n where
x is the raw score
μ is the population mean
σ is the population standard deviation.
(1) If 36 men are randomly selected, find the probability that they have a mean weight greater than 160lb.
For x > 160 lb
z = 160 - 172/29/√36
z = 160 - 172/29/6
z = -2.48276
Probability value from Z-Table:
P(x<160) = 0.0065185
P(x>160) = 1 - P(x<160) = 0.99348
(2) If 81 men randomly selected, find the probability that they have a mean weight between 170lb and 175lb.
For x = 170 lb
z = 170 - 172/29/√81
z = 170 - 172/29/9
z = -0.62069
Probability value from Z-Table:
P(x = 170) = 0.2674
For x = 175 lb
z = 175 - 172/29/√36
z = 175- 172/29/6
z = 0.93103
Probability value from Z-Table:
P(x = 175) = 0.82408
The probability that they have a mean weight between 170lb and 175lb is calculated as:
P(x = 175) - P(x = 170)
0.82408 - 0.2674
= 0.55668
