Null hypothesis

Question

A sample is selected from a population with µ=150. After a treatment is administered to the individuals, the sample mean is found to be M=138 and the variance S²=121(S=11). If the sample has n=18 scores, then calculate the estimated standard error and determine whether the sample is sufficient to conclude that the treatment has significant effect. Use a two-tail test with ∞= 0.02. (Assume the population is normally distributed)

A) The null hypothesis (H_o)

B) The alternative hypothesis (H_a)

C) The critical value

D) The test statistic

E) Your decision about H_o

F) Your conclusion about the claim

Answer 1

Ho: mu = 150

Ha: mu < 150

alpha = 0.02 and Degrees of freedom = n - 1 = 17

from t-table critical value is -2.224

standard error = 11/sqrt(18) = 2.59

test statistic is t = (138-150)/2.59 = -4.63

since test statistic < critical value, reject Ho

There is evidence to conclude the treatment has a significance effect at alpha = 0.02.