You measure the length of 5 radish seedlings at 7 days and 10 days and get the following results in mm (do NOT use R except for part (d)):

seedling #: 1 2 3 4 5 y s

5 days: 30 20 38 49 32 33.8 10.686

7 days: 37 24 45 52 37 39 10.464

difference: -7 -4 -7 -3 -5 -5.2 1.789

(a) Is there a difference in length?

(b) Repeat (a), but now use a regular (unpaired) t-test.

(c) What happened in (b)?

(d) Verify the normal distribution assumption for the paired t-test you did in (a). (You may use R for this part).