Question

Please help!

Student	# keys	Student	# keys	Student	# keys
1	0	9	5	17	3
2	2	10	1	18	3
3	4	11	5	19	2
4	2	12	3	20	7
5	3	13	2	21	3
6	2	14	4	22	2
7	0	15	0
8	3	16	1

4. Make a dot plot of the distribution of the number of keys carried. Does the sample distribution reveal any marked departures from normality? Explain.

5. Compute a 95% confidence interval for m, the mean number of keys carried among all students at the college. (The standard deviation of this sample is s = 1.74)

6. How many of the sample values fall within this interval? What percentage of the students sampled is this? Should the percentage be close to 95%? Explain.

Answer 1

a)

Deplot or number of hogyan Dotplot of Number of keys 5 Number of keys

the distribution of the data looks slightly right skewed.

b) 95% CI for mean number of keys

1 Eta/2.n-18/vn

t_0.025,21 = 2.08

Descriptive Statistics

N	Mean	StDev	SE Mean	95% CI for μ
22	2.59	1.74	0.370	(1.82, 3.36)

μ: mean of Number of keys

c) the values between 1.8 and 3.36 are 2 and 3. there are 12 number of values falls in this range.

the percentage of students sampled to this are 12*100/22 = 54.54%

The percentage should not be close to 95 because the 95% CI means that the mean value of the sample will lie in this 95% CI range for the 95% of the times.