6.43 Many fire stations handle emergency calls for medical assistance as well as calls requesting firefighting equipment. A particular station says that the probability that an incoming call is for medical assistance is .85. This can be expressed as P(call is for medical assistance) 5 .85.

a. Give a relative frequency interpretation of the given probability.

b. What is the probability that a call is not for medical assistance?

c. Assuming that successive calls are independent of one another, calculate the probability that two successive calls will both be for medical assistance.

(Hint: See Example 6.18.)

d. Still assuming independence, calculate the probability that for two successive calls, the first is for medical assistance and the second is not for medical assistance.

e. Still assuming independence, calculate the probability that exactly one of the next two calls will be for medical assistance. (Hint: There are two different possibilities. The one call for medical assistance might be the first call, or it might be the second call.)

f. Do you think that it is reasonable to assume that the requests made in successive calls are independent?

Explain.