The expectation value is given by:

In this case we just have two options, each with probability 1/2, and the values of x are 2 and 9; then we have:

Therefore, the expectation is $6.5
Answer:
2.
x³+2x²+5x+10
x²(x+2)+5(x+2)
taking common
(x+2)(x²+5) is your answer
a³-a²b²-ab+b³
taking common
a²(a-b²)-b(a-b²)
taking common
(a-b²)(a²-b)
1. 1.125
2. 0.08333333333
good luck :)
As a fraction, the exact answer is 5/6
In decimal form, the approximate answer is 0.8333
To get this answer, note how there are 5 ways to roll something that isn't a three (1,2,4,5,6) out of 6 ways total (1,2,3,4,5,6)
So you simply divide the two values to get 5/6 = 0.8333