Answer:
39.10%
Step-by-step explanation:
The given timeout distributions are:
Exp (1/10), Exp (1/12)
The equation to use is the following:
F (x) = 1 - e ^ (- a / b); x> 0
So the probability is:
P (food has not arrived after waiting 25 minutes | R) = e ^ (- 10/10) = 0.3679
P (food has not arrived after waiting 25 minutes | S) = e ^ (- 12/15) = 0.2865
So:
P (food has not arrived after waiting 25 minutes) = (food has not arrived after waiting 25 minutes | R) * P (R) + (food has not arrived after waiting 25 minutes | S) * P (S)
Replacing:
P (food has not arrived after waiting 25 minutes) = 0.3679 * 1/3 + 0.2865 * 2/3 = 0.3136
However:
P (R | food has not arrived after waiting 25 minutes) = (food has not arrived after waiting 25 minutes | R) * P (R) / P (food has not arrived after waiting 25 minutes)
P (R | food has not arrived after waiting 25 minutes) = 0.3679 * 1/3 / 0.3136 = 0.3910
It means that the probability is 39.10%
