Question

If 89 babies are sampled at random from the hospital, what is the probability that the mean weight of the sample babies would differ from the population mean by less than 48 grams

Answer 1

0.6836

Explanation:

(weight - mean weight) = 48

Variance, s² = 204,304

Sample size, n = 89

We need to obtain the Zscore :

Zscore = (X - mean) / standard Error

Zscore = (weight - mean weight ) / (s/√n)

s = √204304 = 452

The difference from the meanncoukdnbe either to the right or left :

Zscore = - 48 / (452/√89) OR 48 / (452/√89)

Zscore = - 48 / 47.911904 OR - 48 / 47.911904

Zscore = - 1.002 or 1.002

P(Z < - 1.002) = 0.1582 (using Z table)

P(Z < 1.002) = 0.8418

P(Z < 1.002) - P(Z < - 1.002)

0.8418 - 0.1582

= 0.6836