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A company has discovered that a recent batch of batteries had manufacturing flaws, and has issued a recall.

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A company has discovered that a recent batch of batteries had manufacturing flaws, and has issued a recall. In a group of 15 batteries covered by the recall, 6 are dead. Two batteries at random are chosen from the package of 15.

a) Has the assumption of independence been met? Explain.
b) Create a probability model for the number of good batteries chosen.
c) What's the expected number of good batteries?
d) What's the standard deviation?

tutor

tutor Added an answer on Jul 05,2019

The standard deviation of this problem?

sqrt(1.86 - 1.2^2) = 0.648

tutor

tutor Added an answer on Jul 05,2019

The expected number of good Batteries = 0*0.143 + 1*0.514 + 2*0.343 = 1.2

tutor

tutor Added an answer on Jul 05,2019

No, because the outcome for the first battery affects the probability that the second battery is dead.

b. Create a probality Model table

Hint: Determine the probabilities associated with each possible value. Since the batteries are chosen without replacement, use conditional probabilities and the General Multiplication Rule, given below, to find each probability.

X(Number good)	P(X=x)
0	0.143
1	0.514
2	0.343

p(X =0) = 6/15 * 5/14 = 0.143

P(X=1) = 6/15*9/14 + 9/15 * 6/14 = 0.514

P(X = 2) = 9/15 * 8/14 = 0.3423

A company has discovered that a recent batch of batteries had manufacturing flaws, and has issued a recall.

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