Question

A biologist obtains 10 bags of different varieties of ginseng seeds from a grower, and needs to determine their maturity to advise the grower if they are ready to be planted. The best method for checking development is to dissect the seeds under the microscope, effectively killing the seeds. The biologist estimates the average number of seeds in each bag to be 3000. Since the seeds are very valuable and dissection is time consuming, the biologist only wants to sample 100 seeds to assess seed maturity. Which of the following sampling methods would provide the necessary information to the biologist to help the grower? A. Randomly select and dissect 10 of the seeds from each of the bags. B. Randomly select and dissect 10 largest seeds from each of the bags. C. Randomly select and dissect a 50 seeds from each of the grower's two favorite varieties. D. Randomly select a bag of seeds and dissect 100 of the seeds from that bag

Answer 1

The answer is...

A. Randomly select and dissect 10 of the seeds from each of the bags.

There are 10 bags each containing almost equal (3000) number of seeds. We can consider each bag as a separate strata. Hence our job is to pick a sample of size 100 from the 10 strata. Now as each bag contains almost equal number of seeds we take sample of equal size (10) from each(10) strata.