a. A contest entrant has a 0.002 probability of winning $12,165. If this is the only prize and the fee is $35, then find the expected value of winning the contest. b. The probability of winning a lottery is 0.125. What is the probability of winning AT LEAST ONCE in twelve trials?

The right answer is:

(a) -10.67

(b) 0.7986

Step-by-step explanation:

(a)

According to the question,

X                          P(X)                  X.P(X)                 X2.P(X)

12130                  0.002               24.26                 294274

-35                      0.998               -34.93                1222.55      

Now,

or,

hence,

The mean will be:

(b)

According to the question,

n = 12

p = 0.125

q = 1 - p

  = 0.875

Now,

⇒

By substituting the values, we get

⇒

⇒                  

⇒                  

⇒                  

⇒                      

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.