To calculate expected value,
We can add up the probability of all possible events.
The 2 possible events are either winning $50 or losing the prize, which is $ - 50
Expected value =
50 x 40 % + (-50) x 60%
= $-10
So the answer is $-10
For this case we have the following equation:
Let 
We have:
By definition, given an equation of the form 
The quadratic formula, to find the solution can be written as:
In this case we have:
Substituting in the quadratic formula we have:
See attached image
Answer:
Option B
15 i am pretty sure i’m probably gonna be wrong
(a) P( fifth one is bad) = P( first 4 are OK) * P(5th is bad)
= (0.98)^4 * 0.02 = 0.0184 or 1.84%
(b) this will be (0.98)^10 = 81.70%
I believe the answer is 4x + 8. you multiply 4 by x which makes 4x. Than you multiply 4 by 2, making 8.
