The time until failure of an electronic device has an exponential distribution with mean 15 months. If a random sample of five such devices are tested, what is the probability that the first failure among the five devices occurs a after 9 months? b before 12 months?

The probability that the first failure occurs among the five devices is given by

(a) 9 months =

(b) 12 months=

Step-by-step explanation:

probability is given as the; number of required outcome/ total number of possible outcome.

answer: option a.

step-by-step explanation:

you know that the quadrilateral opqr ( a four sided figure) is inscribed in circle. this means that all its vertices are on the circle.

then, by definition, the opposite angles of the quadrilateral are supplementary, this means that the sum of their measures is 180 degrees.

you can observe in the figure that the angles ∠opq   and the angle ∠orq   are opposite, therefore:

then, can be used to d to calculate the measure of ∠opq

you would have to sell 24 bracelets.

step-by-step explanation:

84/3.5 = 24