A grocery sells 5kg bags of rice. You purchased four bags of rice over the course of a month and weigh the rice each time. You obtained the following: Week 1: 4.9kg Week 2: 4.7kg Week 3: 5.1kg Week 4: 5.2kg a. What is the percentage error for each measurement? b. What are the percent differences of the measured values between weeks 1 & 2, 2 & 3, and 3 & 4? c. Calculate the mean of the four measured values d. What is the standard deviation for the four values?