1.A sample of blood sugar (in mg/dl) data for workers of a Candy Factory is given below:

140, 135,160, 169, 175, 140, 130, 150, 120, 160, 145,149,130,115,120,125,

110, 105, 143, 137, 140, 140, 121, 132, 116, 100, 133, 104, 115, 107 , 110.

Find the margin of error and a 90% confidence interval for population mean, given that this population follows a Normal distribution with standard deviation of 20.