3. (1 5 points) In a 1999 survey of teachers by USA Today revealed that 85% of t

Question

3. (1 5 points) In a 1999 survey of teachers by USA Today revealed that 85% of teachers had years. If 30 teachers are selected at random, find the probability that at least 1 tencher had encountered a student with such a weapon in the last three years. (If you use the Binomial, justify its use.) ( I 5 points) Information from. the Census Bureau tells us that 2S% of American men have a bachelor's degree or higher. If 15 American men are selected at random, find the mean and standard deviation of the resulting binomial probability distribution (x- number of men with a bachelor's degree or higher.)

Explanation / Answer

3.The required probability is P(X>=1)

=1-P(X=0)

=1-30C0*(1-0.85)^0*0.85^30

=1-0.007=0.993

4.The mean is np=15*0.28=4.2

The standard deviation is: sq rt of np(1-p)=sq rt of 4.2*(1-0.28)=1.73

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