Here are the key steps in hypothesis testing:
1. State the null (H0) and alternative (Ha) hypotheses:
H0: The average daily usage of social media of Sofia's friends is the same as the global average usage (142 minutes).
Ha: The average daily usage of social media of Sofia's friends is not the same as the global average usage.
2. Choose the level of significance:
Most commonly used are 1%, 5%, and 10%. Let's use 5% level of significance or α = 0.05.
3. Collect data and compute the test statistic:
Sofia would need to compute the average daily usage of her friends and the