Answer:
a.The advertising campaigns increased the average daily sales.
Step-by-step explanation:
This is a hypothesis test for the population mean.
The claim is that the advertising campaigns increased the average daily sales.
Then, the null and alternative hypothesis are:
The significance level is 0.05.
The sample has a size n=100.
The sample mean is M=7280.
The standard deviation of the population is known and has a value of σ=1000.
We can calculate the standard error as:
Then, we can calculate the z-statistic as:
This test is a right-tailed test, so the P-value for this test is calculated as:
As the P-value (0.0026) 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 advertising campaigns increased the average daily sales.