Shipping holiday gifts. A local news survey asked 500 randomly sampled Los Angeles residents which shipping carrier they prefer to use for shipping holiday gifts. The table below shows the distribution of responses by age group as well as the expected counts for each cell (shown in parentheses).
Age 18-34 35-54 55+ Total
Shipping Method
USPS 72 (81) 97 (102) 76 (62) 245 UPS 52 (53) 76 (68) 34 (41) 162 FedEx 31 (21) 24 (27) 9 (16) 64 Something else 7 (5) 6 (7) 3 (4) 16 Not sure 3 (5) 6 (5) 4 (3) 13 Total 165 209 126 500
(a) State the null and alternative hypotheses for testing for independence of age and preferred shipping method for holiday gifts among Los Angeles residents.
(b) Are the conditions for inference using a chi-square test satisfied?