Suppose that 30% of all students who have to buy a textbook for Statistics want a new copy (the successes!), while the rest 70% want a used copy. Consider randomly selecting 15 buyers. (a) Find the mean and standard deviation for the number who want to buy a new copy of the book Mean = 15*.3 Standard deviation = sqrt(15*.3*.7) (b) Is that probability that the number of buyers who want new copies is more than two standard deviations away from the mean value? Probability= 1-.984757474+.004747562 (c) The bookstore has 13 new copies and 13 used copies in stock. If 15 people come in one by one to buy this textbook, what is the probability that all 15 will get the type of book they want from current stock? Probability= .999999483-.0352676 Hint: Consider X: the number of buyers who want a new copy. For what values of X will all 15 buyers get what they want? (d) Suppose that new copies cost $134 and used copies cost $67. Assume that the bookstore has currently 15 new copies and 15 used copies. What is the expected total revenue from the sale of the next 15 copies? Expected Revenue=

Step-by-step explanation:

a.

mean = E(X)

= no = 15 x 0.3

= 4.5

Standard deviation

= √np(1-p)

= √15x0.3x0.7

= √3.15

= 1.775

B.

Probability of number of buyers who want new copy

P(x>mean+2sd)

= P(x>4.5+2(1.775))

P(x>8.05)

= 1-(0.984757474+0.004747562)

= 0.01049

= 0.0105

C.

Σ13 (15Cx) x (0.3^x)(0.7)^15-x

= 0.9647

D. (4.5*237)+(15-4.5)*67

= 616.5+703.5

= $1320

Expected revenue from sale of next 15 copies is $1320

y = - 6

step-by-step explanation:

given the point (- 2, y) lies on the graph then it is a solution of it's equation.

substitute x = - 2 into the equation for value of y

y = 3(- 2) = 3 × - 2 = - 6

the point on the graph is (- 2, 6)

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.