3) There are 50 boxes in a factory. Their weights, w kg, are divided into 5 classes, as shown in the following table.
a. Find an estimate for the variance in the weights of the boxes
b. show that the estimated mean weight of the boxes is 32kg
c. There are x boxes labeled fragile. They are all in class E. The estimated mean weight of all the other boxes in the factory is 30 kg. Calculate the value of x
