Quiz STAT

Review Questions

Questions 1-10 classify the following variables as:

a. Nominal

b. Ordinal

c. Ratio

d. Interval

1. __C___ Number of goals scored by a team during a season

2. __C___ Number of audit units Winter quarter students register for

3. __A___ Blood type of white males at LLUMC

4. __B___ Stages of cancer

5. ___A__ Zip codes

6. ___A__ Region of the country (1= East, 2= South, 3= Midwest, 4= West)

7. __A___ Social security numbers

8. __B___ Final letter grades given in data analysis & management class

9. ___A__ Ability of children to reach over their head with their right hand and touch the top of their left ear

10. __C___ Commuting times to work

Questions 11-14 compute the following

ID Waiting time at a bank (in minutes)

1 10

2 17

3 8

4 15

5 12

6 13

7 14

8 16

9 35

10 18

11 35

11. Find the (a) mean, (b) median, (c) mode for the waiting time variable?

a.17.55, b. 15, c. 35

12. Find the (a) variance, (b) standard deviation, (c) range, interquartile range for the waiting time variable?

a. 83.07, b. 9.11, c. 27, d. 6

13. Is there any extreme outliers? If yes, how many?

For extreme outliers:

Upper fence= Q3 + 1.5*IQR= 18 + 9= 27

Lower fence= Q1 – 1.5*IQR= 12 – 9= 3

For extreme outliers:

Upper fence= Q3 + 3*IQR= 18 + 18= 36

Lower fence= Q1 – 3*IQR= 12 – 18= -6

There is no extreme outlier. All outliers are within 1.5 IQR from Q3

14. What the best measure of central tendency to summarize the waiting time?

Median (range): 15 (27) [since, we have two outliers (35& 35) and we cannot confirm if they have big impact on the mean by just using box-plot]

Questions 15-18: Answer the following questions regarding the contingency table:

		Gender	Total
Class attendance		Male	Female
	Yes	9	11
	No	6	4
Total

15. What is the probability of no attendance? [ 10/30=0.33]

16. What is the probability of class attendance among the males? [9/15=0.60]

17. What is the probability of attending class or not attending class? [(20/30) + (10/30)=30/30 =1]

18. What is the probability of attending class and being a male? [(9/15) * (15/30)= 9/30=0.30]

Questions 19-23 In 6 trials of flipping a coin, assuming the chance of getting a tail is 30 %, what is the probability of:

19. Getting 4 tails? P (X=4) = P(X ≤4) – P (X≤ 3) = 0.989 – 0.930= 0.059

20. Getting less than 3 tails? P (X<3) = P (X≤ 2) = 0.744

21. Getting 4 or less tails? P (X≤4) = 0.989

22. Getting 3 or more tails? P (X ≥ 3) = 1 – P (X≤ 2) = 1- 0.744= 0.256

23. Getting more than 4 tails? P (X > 4) = 1- P (X ≤ 4) = 1- 0.989= 0.011

Questions 24-25: Using the standard normal distribution table, find the following:

24. The area under the standard normal curve above Z of 1.54?

Z

[P = 0.5- P1= 0.5- 0.4382= 0.0618]

25. The area under the standard normal curve between a Z of -1.90 and + 1.90?

Z

[P1 = 0.4713 & P2=0.4713 →P= P1+P2= 0.9426]