probability
posted by xiong on .
68 % of kids watch tv daily. out of 12 kids what is the probability that:
a. Exactly six kids watch tv daily
b. Six or less kids watch tv daily
c. Seven or more kids watch tv daily
d. Find the mean for the distribution

This is a case of binomial distribution
Prob(watching) = .68/100 = 17/25
prob(not watching) = 8/25
a) Prob(exactly 6 out of 12 watching)
=C(12,6)(17/25)^6(8/25)^6 = ....
b) prob(6 or less)
= Prob(exactly 1) + Prob(exacly 2) + prob(exactly 3) + .. prob(exactly 6)
= C(12,1)(17/25)(8/25)^11 + C(12,2)(17/25)^2(8/25)^10 + .. + C(12,6)(17/25)^6(8/25)^6
do the others the same way
hope you have a good calculator. 
We can use excel for this. do you know how I would set it up in excel?