Answer:
There is sufficient evidence at 0.05 significant level to support company's claim.
Step-by-step explanation:
We have these informations from the question
n = 1400
P^ = 31% = 0.31
Alpha level = 5% = 0.05
Then we come up with the hypothesis
H0: P = 0.28
H1: P>0.28
From here we calculate the test statistic
z = p^ - p/√pq/n
P = 0.28
q = 1-0.28
= 0.72
z = 0.31-0.28/√(0.31*0.72)/1400
= 0.03/√0.0001594
= 0.03/0.012
= 2.5
Then we have a p value = 0.00621
The p value is less than significance level
0.00621<0.05
So the null hypothesis is rejected.
We conclude that There is sufficient evidence at 0.05 significant level to support company's claim.
