Answer: d, p = 0.4493
Step-by-step explanation: this question is solved using a possion probability distribution because the event is occurring at a fixed rate.
For this question of ours the fixed rate is the fact that 12 customers visiting the shop within 15 minutes.
For this question our fixed rate (u) = 12/15 = 0.8
The probability distribution for possion is given as
P(x=r) = (e^-u * u^r) / r!
At this point x = 0 ( no customers coming to the shop)
P(x=0) =( e^-0.8 * 0.8^0)/ 0!
P(x=0) = (e^-0.8 * 1)/1
P(x=0) = e^-0.8
P(x=0) = 0.4493