Brief explanation pls it's urgent

Question Completion Status: Question 3 (7 marks) Sales in (thousands of dollars) of a new shirt designed for the current temperatures is given below for the first three weeks (Monday to Friday) at JPK Inc. The company wants to use the partial Excel Summary Output and the Time Series data below to develop a regression equation and use seasonal indexes to estimate their sales. Note: time period (t=1, 2, 3, ...) Quarter Sales Yly Week 1 M 47 0.958 T 51 1.031 W 45 0.903 T 56 1.115 F 57 1.127 Week 2 M 46 0.902 T 50 0.974 W 45 0.870 T 59 1.132 F 61 1.162 Week 3 M 48 T 50 W 46 T 57 F 58 a. Calculate the seasonal indexes to three decimal places, show your calculations