A researcher in Colorado is trying to improve plant growth. They want to see how combinations of different brands of grow-lights and plant foods affect plant growth. Three different grow-lights are used: L1, L2 and L3. Two plant foods are used: F1 and F2.

Twenty-four plants are used in the experiment. For each grow- light, eight are randomly selected and exposed to the grow light.

For each grow-light, the plants are split into two groups of four and one group gets plant food F1 and the other gets plant food F2. After 6-weeks, the length of the plants are recorded. For all hypothesis tests use (ð = 0.05)

Source df SS MS

Grow-light ? 253.22 ?

Plant food ? ? 15.78

Interaction ? 10.71 ?

Error 18 ? 9.87

Total ? 457.37

b) Perform a hypothesis test to see if there is significant evidence to conclude that there is an interaction between the grow-light and the plant food used?

c) Perform a hypothesis test to see if there is no difference between the effects of plant foods.

d) Perform a hypothesis test to see if there is no difference between the effects of the different grow-lights