Do wearable devices that monitor diet and physical activity help people lose weight? Researchers had 237 subjects, already involved in a program of diet and exercise, use wearable technology for 24 months. They measured their weight (in kilograms) before using the technology and 24 months after using the technology. - Explain why the proper procedure to compare the mean weight before using the wearable technology and 24 months after using the wearable technology is a matched pairs t-test. Choose the correct explanation.

a.) A person's weight before and after wearing the device would be independent; thus, the data from this before and after study should be analyzed using a matched pairs t-test.

b.) A person's weight before and after wearing the device would not be independent; thus, the data from this before and after study should not be analyzed using a matched pairs t-test.

c.) A person's weight before and after wearing the device would be independent; thus, the data from this before and after study should not be analyzed using a matched pairs t-test.

d.) A person's weight before and after wearing the device would not be independent; thus, the data from this before and after study should be analyzed using a matched pairs t-test. - The 237 differences in weight (weight after 24 months minus weight before using the wearable technology) are x??=?3.5and s=7.8. Let ? be the mean weight difference (weight after 24 months minus weight before using the wearable technology). Complete the test to see if there is significant evidence of a reduction in weight after using the wearable technology. What is the correct null and alternative hypothesis?

a.) H0:?>0 versus Ha:?<0

b.) H0:?=0 versus Ha:?<0

c.) H0:?=0 versus Ha:??0

d.) H0:?<0 versus Ha:?=0