Quiz 2

 

Each question is worth 1 point.

 

 

1.     You draw two cards from a deck, what is the probability that:

 

a.     Both of them are face cards (king, queen, or jack)? 

 

b.    You draw two cards from a deck and both of them are hearts?

 

 

 

2.     Assume adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 15.

 

a.     Find the probability that a randomly selected adult has IQ < 115 

 

b.    Find the probability that a randomly selected adult has IQ > 70 

 

c.     Find P30, which is the IQ separating the bottom 30% from the top 70%

 

 

 

3.     a.  When would the mean grade in a class on a final exam be considered a statistic? 

 

b. When would it be considered a parameter? 

 

c.    Define bias in terms of expected value.

  

d.     Is it possible for a statistic to be unbiased yet very imprecise? Can it be accurate but biased?

 

 

4. a.  Why is a 99% confidence interval wider than a 95% confidence interval? 

 

b. When you construct a 95% confidence interval, what are you 95% confident about?

 

 

5.    My parents lived in Florida and wanted to know the probability of winning the Florida Fantasy 5 if they bought one ticket. They had to pick the five winning numbers from 1-36. Each randomly selected number is different and order doesn’t matter. What is the Probability of their winning?

 

 

6.   In a study of families with children with disabilities, group of 6 US households were randomly selected. In the table below, the random variable x represents the number of households among 6 that had a child with a disability living there.

 

 

x

P(x)

0

0.539

1

0.351

2

0.095

3

0.014

4

0.001

5

0+

6

0+

 

 

a)     Is this a probability distribution?

 

b)    What is the mean?

 

c)     What is the standard deviation?

 

 

7.   Ten peas are generated from parents having the green/yellow pair of genes so there is a 75% probability that an individual pea will have a green pod. Find the probability that among the 10 offspring peas, at least 9 have green pods. Is this unusual? Explain.

 

8. Find the critical value:

 

a. Z0.02

 

 b. Z0.01

  

 

c. Z0.10

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