Please can you give the formula to do this exercise, Thank you.

A sample of 40 investment customers serviced by an account manager are found to have had an average of $23,000 in transactions during the past year, with a standard deviation of $8500. A sample of 30 customers serviced by another account manger averaged $28,000 in transaction, with a standard deviation of $11,000. Assuming the population standard deviations are equal, use the 0.05 level of significance in testing whether the population means could be equal for customers serviced by the two accounts manages. Using the appropriate statistical table, what is the most accurate statement we can make about the p-value for this test? Construct and interpret the 95% confidence interval for the difference between the population means.

Z = (mean 1 - mean 2)/sq rt of (SD1^2 + SD2^2)

Find P as smallest value in table labeled something like "areas under normal distribution."

95% confidence interval = mean ± 1.96 SD

I hope this helps. Thanks for asking.