Question: A market researcher wants to test to determine if families of four in City A spend less per week, on average, than families of four in City B on dining out. To accomplish this, the market researcher randomly 50 families of four from City A and 60 families of four from City B and has them all keep a log of their dining out spending for one week. The sample mean for City A is $165 with a standard deviation of $55. The sample mean for City B is $207 with a standard deviation of $65. Assuming an alpha of .05, the observed z value is:
a) -1.46
b) -3.18
c) -3.67
d) -2.38