A grocery store has an average sales of $8000 per day. The store introduced several advertising campaigns in order to increase sales. To determine whether or not the advertising campaigns have been effective in increasing sales, a sample of 64 days of sales was selected. It was found that the average was $8300 per day. From past information, it is known that the standard deviation of the population is $1200. The correct null hypothesis for this problem is

We need to conduct a hypothesis in order to check if the true mean for sales is significantly higher than 8000, the system of hypothesis would be:  

Null hypothesis:  

Alternative hypothesis:  

Step-by-step explanation:

Data given  

represent the sample mean  for the sales

represent the population standard deviation

sample size  

represent the value that we want to test

z would represent the statistic (variable of interest)  

System of hypothesis

We need to conduct a hypothesis in order to check if the true mean for sales is significantly higher than 8000, the system of hypothesis would be:  

Null hypothesis:  

Alternative hypothesis:  

The statistic to check this hypothesis is given by:

 (1)  

Calculate the statistic

P-value

Since is a one right tailed test the p value would be: