Question

Every year, the veterinary hospital at a major research university treats a number of horses that have stones called enteroliths in their guts. A sample of 20 years shows that on average about 2% of horses presenting at the veterinary hospital are treated for enteroliths. Some breeds of horses seem more prone to developing enteroliths than others. Below is a table with the distribution of enteroliths among the breeds. Breed Arabian Thoroughbred Appaloosa Morgan Quarter horse Probability 0.3 .2 .15 .10 ? The probability that a horse arriving at the veterinary hospital is not an Arabian or a quarter horse is: (a) 0.55. (b) 0.25. (c) 0.45. (d) 0.75.

Answer 1

(c) 0.45

Explanation:

Arabian = P(Ar) = 0.30

Thoroughbred = P(T) = 0.20

Appaloosa = P(Ap) = 0.15

Morgan= P(M) = 0.10

Quarter horse = P(Q) = ?

The probability of horse not being an Arabian or a quarter horse is the sum of the probabilities of a horse being any of the remaining breeds (Thoroughbred, Appaloosa, Morgan):

`P= P(Ap)+P(T)+ P(M)\\P=0.2+0.15+0.1\\P=0.45`

The probability is 0.45.