In semiconductor manufacturing, wet chemical etching is often used to remove silicon from the backs of wafers prior to metalization. the etch rate is an important characteristic in this process and known to follow a normal distribution. two different etching solutions have been compared, using two random samples of 10 wafers for each solution. assume the variances are equal. the etch rates are as follows (in mils per minute): solution 1 solution 2 9.7 10.6 10.5 10.3 9.4 10.3 10.6 10.2 9.3 10.0 10.7 10.7 9.6 10.3 10.4 10.4 10.2 10.1 10.5 10.3 calculate sample means of solution 1 and solution 2

At the olympic games, many events have several rounds of competition. one of these events is the men's 100-meter backstroke. the upper dot plot shows the times (in seconds) of the top 8 finishers in the final round of the 2012 olympics. the lower dot plot shows the times of the same 8 swimmers, but in the semifinal round. which pieces of information can be gathered from these dot plots? (remember that lower swim times are faster.) choose all answers that apply: a: the swimmers had faster times on average in the final round. b: the times in the final round vary noticeably more than the times in the semifinal round. c: none of the above.