Question 909169
a) Poisson Distribution (<u>average</u> = 10 per day):
P( x >10) = 1 - poissoncdf(10,10)
P( x < 15) = poissoncdf(10,14) 
P(x &#8805; 20) = 1 - poisson(10,19)
b) Binomial Distribution (parents pay 0r don't pay)
p(pay) = .85,  n = 15
c)P(x = 15) = binompdf(15, .80, 15) = .85^15
P(x  &#8805;  10) = 1 - binomcdf(15, .85, 9)
Using {{{P (x)= highlight_green(nCx)(p^x)(q)^(n-x) }}} = 15C15(.85)^15(.15)^0
p and q are the probabilities of success and failure respectively. 
In this case p= .85, q = .15 , n = 15
{{{nCx = (n!)/x!(n - x)!)}}}