A population has a mean of 300 and a standard deviation of 18. A sample of 144 observations will be taken. The probability that the sample mean will be between 297 to 303 is: a. 0.9545.
b. 0.9332.
c. 0.0668.
d. 0.4332.

0.9545

Step-by-step explanation:

Given that :

Mean = 300

Standard deviation, σ = 18

Sample size, n = 144

Zscore = (x - mean) ÷ σ/√n

At score, x = 297

Zscore = (297 - 300) / (18/12) = - 2

P(Z< - 2) = 0.02275

At score, x = 303

Zscore = (303 - 300) / (18/12) = 2

P(Z< 2) = 0.97725

P(Z < 2) - P(Z < - 2) = 0.97725 - 0.02275 = 0.9545

this doesn't make sense lol