Okay, so the answer for the first two questions are...
E(Q) = n * p , where n are number of trials and p is probability...
When n is unknown and E(Q) is 6 and p is 0,04, then
n = 6/0,04 = 150.
X1 = 50 and X2 = 50, so Y = x1 + x2 = 100, so n = 100.
Var(Y) = n * p * q , where n are number of trials, p is probability and q is (1 - p)
Var(Y) = 100 * 0,04 (1 - 0,04) = 3,84.
E(Y) = n * p = 100 * 0,04 = 4.
I'm however still having trouble with the next questions...
I tried to put up a binomial distribution two answer C, but as the answer is supposed to be 0.785, it doesn't match my answer of 0,78837. So it is probably wrong... Any ideas?
The answer is...
P(Y<=5) = SUM from k = 0 to 5 of ( (100*0,04)^k / k! ) * exp(-100*0,04) = 0,78513.
and the answer for the last question is .322..?