Which one of the following examples does would use a test for two independent samples? i.e. for which scenario would the pooled t-test apply? (only one uses pooled. the other 3 used paired)
a. A study comparing the yields for two varieties of wheat is conducted. 30 test plots are randomly selected. 15 of those plots are randomly selected to be planted with variety A and the remaining 15 plots are planted with variety B.
b. A comparison of delivery times between two pizza restaurants is conducted. At 15 randomly selected times, the same pizza is ordered from each of the two restaurants and the delivery times are recorded.
c. A study is conducted to compare the effect of a diet plan on weight loss. 100 obese people are randomly selected. All 100 are instructed to follow the diet plan. Their weights are measured before they start the diet and again after they have been on the diet for 6 months.
d. For 15 randomly selected food items, the prices advertised in the local newspaper by two competing supermarkets are recorded. A hypothesis test is then performed to see if there is any mean difference in the prices offered by the two supermarkets.