Question

Xavier determined that some fish like to eat worms, some like to eat shrimp, and others don't like to eat worms or shrimp. He calculated the probabilities and created the Venn diagram below: What is the probability that a fish eats worms, given that it eats shrimp?

A) 0.2
B) 0.3
C) 0.33
D) 0.67

Answer 1

The answer is letter C - 0.33.

The conditional probability formula for the probability of A given B is
P(A l B) = P (A and B) over P (B)

In this case, it's
P (worms l shrimp) = P (worms and shrimp) over P (shrimp)
P (worms l shrimp) = P (0.2) over P (0.2 + 0.4)
P (worms l shrimp) = P (0.2) over P (0.6)
P (worms l shrimp) = 0.33