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 s

5 days: 30 20 38 49 32 33.8 10.686

7 days: 35 27 46 58 34 40 12.145

difference: -5 -7 -8 -9 -2 -6.2 2.775

(a) Is there a difference in length? (Note: this should be one-sided. Why??)

(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).