Your company invented an app for people to join exercise groups and share their progress with their group members. From Apr. 1 2019, one new feature...

Your company invented an app for people to join exercise groups and share their progress with their group members. From Apr. 1 2019, one new feature is added. By this feature, people also take photos and share their meals and snacks during the day with their group members. This new feature is supposed to help people to keep fit and healthy.

As a first step of market testing, you launch this new feature to 100 random groups (each group around 8 to 11 people), 1000 people in total. And you also randomly select another 1000 people who have not seen this feature as control group (for comparison).

For 1000 people who sharing both exercise and diet:

·     sample mean of weight loss=5.9 kg

·     sample standard deviation =4.1 kg

·     sample size =n=1000

For 1000 people who only sharing exercise data:

·     sample mean of weight loss=4.1 kg

·     sample standard deviation =3.7 kg

·     sample size =n=1000

You want to test whether the new feature really help people to lose weight and keep fit.

Q1. What is your Null hypothesis and what is your alternative hypothesis?

Q2. Test your hypothesis and summarize your conclusion