Solve the problem.
-The length of telephone calls (in minutes) in a public telephone booth has the probability density function: Determine the probability that a call selected at random will last longer than seven minutes. (Round answer to two decimal places.)
A) 0.42
B) 0.31
C) 0.39
D) 0.54

Question

Solve the problem.
-The length of telephone calls (in minutes) in a public telephone booth has the probability density function:  Determine the probability that a call selected at random will last longer than seven minutes. (Round answer to two decimal places.)
A) 0.42 
B) 0.31 
C) 0.39 
D) 0.54

Quizplus · Accepted Answer

To find the probability that a call selected at random will last longer than seven minutes, we need to find the integral of the probability density function from 7 to infinity:

∫[7,∞] 6x⁻⁷ dx

= [-6x⁻⁶] [7,∞]

= 6/7

≈ 0.31

Therefore, the answer is (B) 0.31, rounded to two decimal places.

Solve the Problem. -The Length of Telephone Calls (In Minutes) in a Public