Simple random vs stratified sampling. Facilities A and B account for 60% and 40%, respectively, of the production of a certain electronic component. The components from the two facilities are shipped to a packaging location where they are mixed and packaged. A sample of size 100 will be used to estimate the expected life time in the combined population. Use the MSE criterion to decide which of the following two sampling schemes should be adopted:

(a) simple random sampling at the packaging location, and

(b) stratified random sampling based on a simple random sample of size 60 from facility A and a simple random sample of size 40 from facility B.