CK-12 Probability and Statistics - Advanced

http://www.ck12.org Chapter 7. Sampling Distributions and Estimations

If you so desire, you can transfer this data into your own table:

TABLE7.4:

Number Not Registered Probability

0 0. 72893

1 0. 23982

2 0. 02959

3 0. 00162

4 0. 00003

Lesson Summary

In this lesson you have learned that the random variableXhas a binomial distribution ifXrepresents the number of
“successes” innindependent trials. In each of these trials, the probability of success isp. You have also learned that
a binomial distribution has these important features:

• The probability of getting exactlyX=ksuccesses is given by the formula

P(X=k) =

(

n

k

)

pk( 1 −p)n−k

• The mean or expected value is represented by

E(X) =n p=μx

• The standard deviation is

σx=

√

n p( 1 −p)

Review Questions

1. According to the Canadian census of 2006, the median annual family income for families in Nova Scotia is
   $56,400. [Source: Stats Canada.www.statcan.ca ]. Consider a random sample of 24 Nova Scotia households.