If you look at the graph for the U.S. stock and bond returns, it appears that bond returns have become stronger and more volatile in the second half of the period we examined.1.We want to know if bond returns in the period from 1973-2018 are different from bond returns from 1928-1972.Devise null and alternative hypotheses that address this statement.2.Compute mean return, standard deviation, standard error, and t-statistic for each bond return sample. Extend your analysis to determine whether the mean return for each sample is significantly different from zero at the 5% level. Provide a brief intuitive explanation for your conclusion regarding statistical significance.3.Now, let's get back to the comparison of the two bond return samples.In this example, there is no particular reason for calculating the vector of differences. (Which years should be paired up?) So, use the TTEST function in Excel to calculate the p-value.Assume the variances for the two samples are different. (This is a more conservative test.) Use the TINV function to back out the t-statistic for the test.(Note: Use 58 degrees of freedom for this test.)Can you reject the null hypothesis at the 5% level? Provide a brief explanation of your answer to this question