Choose the One Alternative That Best Completes the Statement or Answers

Multiple Choice

Choose the one alternative that best completes the statement or answers the question.
Solve the problem.
-Between 7:00 AM and 8:00 AM, trains arrive at a subway station at a rate of 15 trains per hour (0.25 trains per minute) . The following formula from statistics can be used to determine the probability that a train will arrive within t
Minutes of 7:00 AM. $$F ( t ) = 1 - e ^ { - 0.25 t }$$ Determine how many minutes are needed for the probability to reach 20%.

A) $0.89 \mathrm {~min}$
B) $2.35 \mathrm {~min}$
C) $5.34 \mathrm {~min}$
D) $4.12 \mathrm {~min}$