Please, solve this question for me.

Many studies have confirmed that in the population, the flu lasts 21 days on average with a standard deviation of 7. The manufacturers of Tamiflu want to show that their product reduces the length of the flu. They choose a sample of 25 people for their experiment and give them Tamiflu at the start of their flu. The average length of the flu among the 25 people taking Tamiflu was 18 days. If you ran a test to determine if Tamiflu does reduce the length of a flu, what is the null hypothesis? Using an alpha level or p critical of 0.05, use statistics to show if there is a statistically significant difference in the average length of time with and without taking Tamiflu. Show all of your work to prove this and indicate if you would reject your null hypothesis and why or why not. Write a paragraph to explain your results to a nontechnical audience. Write a paragraph to explain your results in a scholarly journal.