roblem \#4 4. (2 points) - Street Research Inc. collected a random sample of 50 consumers among a population of credit card customers and their respective annual credit card charges in 2021, which is presented to you on "Problem \#4" Excel file. a. (0.5 point ) - Develop a point estimate of the mean annual credit card charge based on the sample of 50 consumers. b. (0.5 point ) - Develop a point estimate of the population standard deviation for annual credit card charge. c. ( 1 point ) - Assume that the population of credit card customers has a standard deviation of =$2,000.00 for the annual credit card charges in 2021. Discuss the reason(s) for the difference between the population standard deviation value and the point estimate for standard deviation you calculated in topic (b) for the sample of 50 consumers provided. 6. (4 points) - Street Research Inc. is presenting to you the same random sample of 50 consumers among a population of credit card customers and their respective annual credit card charges in 2021 , now found in "Problem \#6" Excel file. a. (2 points) - Using the random sample provided, apply equation 6.7 from your textbook, calculate the interval estimate for the mean annual credit card charges, by using confidence level at 95% and 99%. Discuss the difference between these two estimated intervals. b. (2 points) - Repeat the calculations of the interval estimate for the mean annual credit card charges at 95% and 99% confidence, but at this time you must use the Descriptive Statistics function from MS-Excel's Data Analysis toolbox