use 4 decimals.

Market Researchers have become more interested in the potential of social networking sites. But they need to understand the demographics of social networking users. A recent survey showed that 22 of the 30 respondents who reported earning less than $30,000 per year said that they were social networking users. The mean salary of the 22 respondents was $21,500 with a standard deviation of $200. On the other hand, 20 of the 30 respondents who reported earning more than $70,000 per year said that they were social networking users. The mean salary of the 20 respondents was $90,000 with a standard deviation of 5300. (Note: IN ORDER TO GET FULL MARKS, SHOW ALL CALCULATION STEPS. FAILURE TO DO SO WILL RESULT IN A SCORE OF \"0\".) (a) Is there is enough evidence to infer that those who reported earning more than $70,000 per year are more likely to be social networking users? Assume that the level of significance is 2.5%. (b) Estimate with 98% confidence the variance of salaries of the entire population of social network users earning less than $30,000 per year