Please every step in the calculation The shell of the snail Cepaea nemoralis can
ID: 313981 • Letter: P
Question
Please every step in the calculation
The shell of the snail Cepaea nemoralis can be yellow, pink, or brown. Suppose that a very large natural population of this species consists of 27% yellow, 39% pink, and 34% brown individuals. If you randomly sample 2 snails from this population, what is the probability that
(a) both are yellow?
(b) neither is yellow?
(c) one is yellow and one is not?
[Hint: when taking a small sample from a very large population, sampling without replacement is essentially the same as sampling with replacement since removing a few individuals does not significantly alter the makeup of the population.]
Explanation / Answer
(a) both are yellow?
Probability of sampling yellow snail = 27/100 = 0.27
the probability of two (or more) independent events occurring together can be calculated by multiplying the individual probabilities of the events.
=0.27 x 0.27 = 0.072 = 7.2%
(b) neither is yellow?
Probability of sampling a non yellow snail = 0.39+0.34 =0.73
= 0.73 x 0.73 =0.53 = 53%
(c) one is yellow and one is not?
Probability of sampling yellow snail = 27/100 = 0.27
Probability of sampling a non yellow snail = 0.39+0.34 =0.73