3 easy statistics questions

(Please show the work in text, not an image, please!!)

1. A random sample of 180 microbiology students were asked how many science classes he or she was enrolled in August 1990. The results showed a mean of 1.83 science classes with a standard deviation of 1.48. Fifteen years later, a similar survey was conducted to determine if the distribution changed. The 2005 sample mean was 1.94 with a standard deviation of 1.62. Do the data provide statistical evidence that the mean number of science classes taken in the first survey is different from the survey taken 15 years later? Perform the appropriate test using = 0.05.

2. Eighteen middle-aged women with platelet readings between 120,000 platelets per microliter and 150,000 platelets per microliter of blood were selected randomly from the population of similar female patients at a large local hospital. Nine of the 18 women were assigned randomly to group A and received a placebo. The other nine women were assigned to group B and received a new platelet drug. After four months, posttreatment platelet readings were taken for all 18 women and were compared with pretreatment readings. The reduction in platelet level (Pretreatment reading Posttreatment reading) for each woman in the study is shown here. Group A (placebo) increase (in platelets per microliter): 2,000, 5,000, 7,050, 10,125, 12,345, 17,350, 13,250, 12,200, 9,125 Group B (platelet drug) increase (platelets per microliter): 28,450, 23,438, 36,380, 12,450, 16,100, 21,350, 39,400, 41,000, 14,325 Part A: Do the data provide convincing evidence, at the = 0.05 level, that the platelet drug is effective in producing a reduction in mean platelet level? Part B: Create & interpret a 95% confidence interval for the difference in the placebo and the new drug.

3. The average speed of a hockey puck slap shot is 73 miles per hour. Monica practiced a new technique to improve her slap shot speed. Her coach recorded the speed of 39 random shots during practice and found that her average speed using the new technique was 75.2 miles per hour, with a standard deviation of 4.1 miles per hour. Part A: State the correct hypotheses if Monica is trying to prove the new technique is an improvement over the old technique.

Part B: Identify the correct test and check the appropriate conditions.