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50% of visitors in an exhibition will buy book A, 30% will buy book B, and 20% are just looking around the exhibition. Suppose that there are 10 visitors. a) Find the probability that if 10 visitors are in the exhibition, 4 will buy book A and 2 will buy book B. b) Find the expected number of visitors that buy book A. c) Find the expected number of visitors that buy book A, if 3 customers are looking around.

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Related textbook solutions

Introductory Statistics
OER Edition, 2013
Openstax
ISBN: 9781938168208

Related questions

Let X denote the number of Canon digital cameras sold during
a particular week by a certain store. The pmf of X is
x | 0 1 2 3 4
pX(x) | .1 .2 .3 .25 .15
Sixty percent of all customers who purchase these cameras
also buy an extended warranty. Let Y denote the number of
purchasers during this week who buy an extended warranty.

a. What is P(X =4, Y = 2)? [Hint: This probability equals
P(Y = 2 I X = 4) * P(X = 4); now think of the four purchases
as four trials of a binomial experiment, with success
on a trial corresponding to buying an extended warranty.]
b. Calculate P(X = Y).
c. Determine the joint pmf of X and Y and then the marginal
pmf of Y.

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a. If the score recorded in the grade book is the total number of points earned on the two parts, what is the expected recorded score E (X+ Y)?

b. If the maximum of the two scores is recorded, what is the expected recorded score?

Ā 

Ā 

in proof testing of circuit boards, the probabilityĀ hat anyparticular diode will fail is 0.01.
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How manydiodes would you expect to fail,Ā and what is the standarddeviation of the number that are expected to fail?Ā 

What is the (approximate) probabilityĀ that atleast four diodes will fail on a randomly selected board?

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