1: You should get a t-value of -2.56611 and a P-value of .030381. Since this is less than 0.05, we "reject the null hypothesis" and claim that the mean number of children is not 2.53 - it has significantly changed.

2: You should get a t-value of .701953 and a P-value of .49178. This means we do not have enough evidence to claim that the means are different. (Mean of 2001 = 55.2 vs Mean of 2003 = 52.4)

3. 

From this Excel chart we can conclude that there is a small, positive, linear relationship between hours of sleep and quiz score. To confirm a relationship, we would need to look at the correlation.

Both histograms look bimodal - students are prone to getting a lot of sleep or very little sleep. But in the quiz score histogram, the spike is only one student, so I would say the histogram is actually fairly flat - the students have achieved a wide variety of scores.

4.  You should get 0.860514 or 86.05% of the students passing. With 104 students, you should expect 104*0.863494 or 89.4935 students to pass. (Round it down to 89.)

The graph looks like this:

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