Question 1066663
a. None requires is .88^9=0.3165
b. for 1 is 9*(.12)(.88^8)=0.3884
c.for 2 is 36*(.12)^2(.88^7)=0.2119
fewer than 3 means 0,1,2 or the sum of the above 3, which is 0.9168.
This is a binomial
The mean is np=9*0.12=1.08 vehicles
the sd is the sqrt of the variance, which is np(1-p)=1.08*.88=.9504; sqrt (.9504)=0.9749.
The above 0,1,2 are calculated from nCx(.12^x)(.88^(n-x))