Each month, the U.S. census bureau mails survey forms to 250,000 U.S. households asking questions about the people living in the household and about such things as motor vehicles and housing costs. Telephone calls are made to households that don't return the form. In one month, responses were obtained from 240,000 of the households contacted. The sample is
A. all U.S. households.
B. the 240,000 households that respond.
C. the 250,000 households initially contacted.
D. the 10,000 households that did not respond.
When you look up a z-score in table A, the number returned from the table is the
A. cumulative proportion.
B. number of individuals with that z-score.
C. area under the curve to right of z.
D. area under the curve between -z and z.