When a virus is placed on a tobacco leaf, small lesions appear on the leaf. To compare the mean number of lesions produced by tw
o different strains of virus, one strain is applied to half of each of 8 tobacco leaves, and the other strain is applied to the other half of each leaf. The strain that goes on the right half of the leaf is decided by a coin flip. The lesions that appear on each half are then counted. The data are given below: Leaf Strian 1 Strain 2
1 31 18
2 20 17
3 18 14
4 17 11
5 9 10
6 8 7
7 10 5
8 7 6
What is the number of degrees of freedom associated with the apropriate t-test for testing to see if there is a difference between the mean number of lesions per leaf produced by the two strains?
a. 7.
b. 8.
c. 11.
d. 14.
e, 16.
Step-by-step explanation: <u>Degrees</u> <u>of</u> <u>Freedom</u> is the number of values "allowed" to vary. For example:
In the experiment above, the sample has 8 tobacco leaves. Two strains will be applied to each leaf. The decision of which strain goes to the right or left is random. Each strain have 7 possible leaves it can be applied, because, for the last, the eight leaf, there is no choice.
Therefore, the degrees of freedom for this experiment is 7.