Hello, Can you please help me with Math Statistics.

Q1) A survey is to be conducted to estimate the sales of Acme Glue. Acme want to be 95% confident that the estimate is no more than 10.5 litres away from the actual average, what sample size is needed? Previous data has indicated that the standard deviation of sales is approximately 6 litres.

Q2) Given the marathon running times for 8 runners from a running club (below). The manager of the club has hypothesized that with additional training, the average time could be lowered to 175 minutes. Compute the test statistic. What does this tell you?

Runner number	Time (mins)
1	185
2	244
3	131
4	154
5	135
6	192
7	201
8	199