An advertising executive wants to determine if a new billboard placed in a city caused sales of their product to increase. To do this, he selects ten random stores that sell the product on the...

An advertising executive wants to determine if a new billboard placed in a city caused sales of their product to increase. To do this, he selects ten random stores that sell the product on the billboard and compares the amount sold in one business cycle before the billboard was placed to the sales of one business cycle after. If we let d=sales after−sales before, what are the null and hypotheses for a hypothesis test on the mean of the differences for the paired data in the population?

Select the correct answer below:

A) H0:μd=0

     Ha:μd>0

B) H0:μd=0

     Ha:μd<>

C) H0:μd<>

     Ha:μd=0

D) H0:μd=0

     Ha:μd≠0