Question

1. The following data represents the exam scores of students in Econ 220 VV22, which is one of several sections of Econ 220 in a college. You can take this as a sample.

                                                               

Student	Score
1	82
2	70
3	50
4	60
5	75
6	65
7	55
8	80
9	85
10	90
11	95
12	94
13	35
14	40
15	65
16	95
17	91
18	55
19	65
20	76
21	86
22	96
23	84
24	57
25	77
26	87
27	90
28	68
29	88
30	89
31	90
32	92

1. Compute the standard deviation (you may use excel)

2. Construct a 95% confidence interval.
3. What is the probability that a randomly selected student scores more than 90.
4. What is the probability that a randomly selected student scores less 90.
5. What is the probability that a randomly selected student scores between 30 and 95?

Answer 1

Using excel you will find that for the sample

for 95% confidence interval

Z= 1.96

Therefore the 95% confidence interval is (69.99,81.69)

b)

P(X>90) = 1- P(X<=90)

c)

d)