Using excel formulas answer

According to Phones-R-Us, the average battery life on a new Model X phone is 28 hours with a standard deviation of 4.3 hours. Using a recent test of refurbished Model X phones, the company wishes to determine if the average battery life of refurbished phones of this model is significantly different at the 5% significance level. In using a collection of forty-five randomly selected refurbished Model X phones, they found an average battery life of 26.8 hours.
a.	Give the null and alternative hypotheses for this test.
		H0:
		H1:
b.	Determine the value of the test statistic.
c.	Determine the appropriate critical value(s).
d	Determine the P-value.
e.	Is there sufficient evidence at the 5% significance level to believe the mean battery life on refurbished versions of the Model X is different from that on new Model X phones? Explain your reasoning.