We randomly sample 50 items from Target stores and note the price for each. Then we visit Walmart and collect the price for each of those same 50 items. Should we use a paired or non-paired test?

A paired t-test

Step-by-step explanation:

Number of items = 50

Variable in question = Price of each item

Classification of items = Similar or Same items

Locations from where items are drawn = 2 locations

The locations = Target Store & Walmart Store

Type of test to use = PAIRED TEST

This is because the items are same or similar and their comparison is the comparison of the mean values of two related groups. In this case, it is not immediately concluded that both groups have equal variance.

i assume that by 5 you mean 5 gallons.

(20)(0.25) = 15

removing 15 gallons reduces the tank from 20 to 5.