Embed Size (px)
Citation preview
1
Basic Statistics ECON 1302
Practice Problems for Chapter 1
Section I: Multiple-Choice 1.
Answer: A
2.
Answer: A
3.
Answer: D
2
4.
Answer: B 5.
Answer: D 6.
Answer: B
3
7.
Answer: A 8.
Answer: D 9.
Answer: B
4
10.
Answer: B 11.
5
Answer: B
6
12.
Answer: B 13.
Answer: A 14.
Answer: C
7
15.
Answer: C 16.
Answer: B 17.
Answer: B
8
18.
Answer: D
19.
Answer: D 20.
Answer: C 21.
Answer: A
9
22.
Answer: C 23.
Answer: D 24.
Answer: A 25.
Answer: C
10
26.
Answer: A 27.
Answer: B 28.
Answer: B 29.
11
Answer: B 30.
Answer: D 31.
Answer: D 32.
Answer: C 33.
Answer: D
12
34.
Answer: D 35.
Answer: C 36.
Answer: B 37.
Answer: C
13
38.
Answer: B 39.
Answer: D 40.
Answer: C 41.
Answer: A 42.
Answer: C
14
43.
Answer: A 44.
Answer: C
15
SECTION II: FREE-RESPONSE PROBLEMS
1. The following data elements represent the amount of time (rounded to the nearest second) that 15 randomly selected customers spent in line before being served at a branch of First County Bank.
183 121 140 198 199 90 62 135 60 175 350 110 185 85 172
(a) Find the five-number summary. (b) Construct a labeled boxplot for this data. Show all your work. (c) Describe the distribution of the amount of time.
Answer:
(a) The five-number summary: Minimum Q1 Median Q3 Maximum
60 90 140 185 350 (b) The boxplot:
IQR=Q3-Q1=185-90=95 Lower fence=Q1-(1.5)IQR=90-(95*1.5)=-52.5 (no outliers) Upper fence=Q3+(1.5)IQR=185+(95*1.5)=327.5 (350 is an outlier) The whiskers should end at 60 and 199.
60 90 140 185 199 350
• 60 90 120 150 180 210 240 270 300 330 360
(c) The distribution of the waiting time looks right skewed due the existence of an
outlier in the upper tail of the distribution. The distribution is centered close to 140-150.
16
2. The salaries of the employees of a corporation are normally distributed with a mean of $25,000 and a standard deviation of $5,000. a. What is the probability that a randomly selected employee will have a starting
salary of at least $31,000? b. What percentage of employees has salaries of less than $12,200? c. What are the minimum and the maximum salaries of the middle 95% of the
employees? d. If sixty-eight of the employees have incomes of at least $35,600, how many
individuals are employed in the corporation? Answers: a. 0.1151 b. 0.52% c. minimum = $15,200 maximum = $34,800 d. 4,000 3. The distribution of SAT scores is normal with 500=µ and .100=σ (a) What proportion of the population have SAT scores above 650?
P(X>650) = .0668 (b) What proportion of the population have SAT scores below 540?
P(X <540) = 0.6554 (c) What is the minimum SAT score needed to be in the highest 20% of the population?
P(X > a ) = .20 then a = 584.16 (d) What SAT scores, X values, separate the middle 70% from the rest of the distribution? P(X < a ) = .15 then a = 396.36 P(X < b) = .85 then b = 603.64
