Question

QUESTION 33 A farmer would like to evaluate Miracle Grow when used on his potted daisy plants. He sets up 20 plants in a room all facing the same window, obtaining the same amount of sunlight, and waters them identically each day. For a month, he monitors how much each plant grows. Then, he adds Miracle Grow to every pot and monitors how much each plant grows during a month with Miracle Grow. At the end of two months, he discovers that 14 plants grew more with Miracle Grow. Test the hypothesis that Miracle Grow increases plant growth (using an alpha level of .01). a) Is this a one-tailed or two-tailed test

Answer 1

a) It is a one-tailed test

Explanation:

The number of plants he sets up in the room, n = 20

The number of plants that grew more with Miracle Grow = 14

The alpha level α = 0.01

A one-tailed test is used when the critical-area of interest in the distribution is either to the left or right of a value on the number line. That is the test is concerned if the test result is either less than or more than a value

In the test the farmer subjects all 20 plants to the same test treatment without any control experiment, therefore, the farmer evaluates the plants based on how much they grow compared to each other, that is if they grow more or less than their pairs

Therefore a one-tailed test should be used.