Answer:
P-value (t=2.58) = 0.0066.
Note: as we are using the sample standard deviation, a t-statistic is appropiate instead os a z-statistic.
As the P-value (0.0066) is smaller than the significance level (0.05), the effect is significant.
The null hypothesis is rejected.
There is enough evidence to support the claim that the population mean μ exceeds 2.4.
Step-by-step explanation:
This is a hypothesis test for the population mean.
The claim is that the population mean μ exceeds 2.4.
Then, the null and alternative hypothesis are:
![H_0: \mu=2.4\\\\H_a:\mu> 2.4](https://tex.z-dn.net/?f=H_0%3A%20%5Cmu%3D2.4%5C%5C%5C%5CH_a%3A%5Cmu%3E%202.4)
The significance level is 0.05.
The sample has a size n=45.
The sample mean is M=2.5.
As the standard deviation of the population is not known, we estimate it with the sample standard deviation, that has a value of s=0.26.
The estimated standard error of the mean is computed using the formula:
Then, we can calculate the t-statistic as:
The degrees of freedom for this sample size are:
![df=n-1=45-1=44](https://tex.z-dn.net/?f=df%3Dn-1%3D45-1%3D44)
This test is a right-tailed test, with 44 degrees of freedom and t=2.58, so the P-value for this test is calculated as (using a t-table):
![P-value=P(t>2.5801)=0.0066](https://tex.z-dn.net/?f=P-value%3DP%28t%3E2.5801%29%3D0.0066)
As the P-value (0.0066) is smaller than the significance level (0.05), the effect is significant.
The null hypothesis is rejected.
There is enough evidence to support the claim that the population mean μ exceeds 2.4.