Answer:
probability = 0.503
Step-by-step explanation:
given data
now = 1:00 p.m
last ghost appearance = 12:35 p.m
solution
we consider here Ghost appearances occur in house according to a Poisson process having a rate = 1.4 ghosts per hour
so time duration from 1:00 pm to 1:30 pm = 0.30 min = 0.5 hrs
and we take random variable denoting inter-arrival time = Y
so here probability that the 7th ghost will appear before 1:30 p.m. is as
probability = P(Y < 0.5)
probability = 1 - [tex]e^{-1.4 \times 0.5)[/tex]
probability = 1 - 0.497
probability = 0.503