Probability

Question 1

Addition rule

Answer 1

‘either’
eg. cards: Pr(queen) + Pr(spade) - Pr(queen of spades)
= 1/13 + 1/4 - 1/52 = 0.308

Question 2

Multiplication rule

Answer 2

‘or’
eg. coin throw: Pr (heads) x Pr (heads) x Pr (heads)
= 1/2 x 1/2 x 1/2 = 0.125

Question 3

sum of probabilities of alleles (diploid)

Answer 3

Pr(A) + Pr(a) = 1

Question 4

sum of probabilities of genotypes (diploid)

Answer 4

Pr(AA) + Pr(Aa) + Pr(aa) = 1

Question 5

how to calculate p + q frequency?

q. 19 AA, 5 Aa, 1 aa?

Answer 5

p/q frequency = no. alleles / total number of alleles (2 x individuals)
A = (2x19) + 5 = 43
a = (2x1) + 5 = 7
divide each by 50 (cos 25 diploid individuals) to get the frequencies of p and q.

Question 6

how would you work out the frequency of q if only p alleles given?

Answer 6

1 - p = q