Question

A simple random sample of 60 adults is obtained from a normally distributed​ population, and each​ person's red blood cell count​ (in cells per​ microliter) is measured. The sample mean is 5.25 and the sample standard deviation is 0.55. Use a 0.05 significance level and the given calculator display to test the claim that the sample is from a population with a mean less than 5.4 comma which is a value often used for the upper limit of the range of normal values. What do the results suggest about the sample​ group?

Answer 1

Explanation:

sample size = n = 60

Sample mean = x bar = 5.25

Sample sd = s = 0.55

Std error of sample = s/sqrt n = 0.071

`H_0: x bar = 5.4\\H_a: x bar <5.4\\`

(One tailed test)

Mean difference = 5.25-5.4 = -0.15

Test statistic t = Mean diff/Se = -2.11

df=59

(since population std dev is not known t test is used)

p value =0.01955

Since p <alpha =0.05 we reject null hypothesis.

The results suggest about the sample​ group that the sample is from a population with a mean less than 5.4