Intro to Business Stat

Exam 2

March 8, 8:00 PM

Instructor: Hadi Farhangi

NOTES:

1. Open book, notes, homework, and additional exercise.

2. There are 6 questions.

3. Internet is NOT allowed unless asked in a question.

4. One calculator is allowed for calculation.

5. Write all your answers on file.

6. The test is worth 125 points.

7. You are required to write out the essential definitions, descriptions, formulas and procedures for getting full score.

8. write in red in front of each question. Take snapshots of your screen and past it in front of a question if needed for Excel calculations. Do not upload any excel file. All answers should be included in a single word document!

9. You are required to read and sign the Honor Code below:

I have neither given nor received aid on this examination,

nor have I concealed any violation of the Honor Code.

Name (print) _____________________________________

Student ID _______________________________________

Initials, date: ___________________________________

Q1. True or False

a. Quartiles divide a set of sorted observations into 5 parts and deciles divide a set of sorted observations into 10 parts ( ).

b. Boxplot shows the different quartiles of data ( ).

c. Line plot and scatter plot show the relationship between two variables ( ).

d. Probability is any value that describe the relative possibility of event that will occur ( ).

e. A random variable is a variable that takes different values with different probabilities ( ).

f. Probability distribution is a listing of some the outcomes of an experiment and the probability associated with each outcome ( ).

Q2. The state department records the number cars passing over a bridge daily to predict the fatigue of the bridge for the future maintenance plan. The daily data for two-week period is as follows:

For this data:

a. Draw box-plot using Excel. Paste the outcome here!

b. Calculate Q1, Q3, D3, D6, P45. Show all steps of calculation.

Q3. Consider the data in the previous question (Q2).

a. Calculate Pearson Skewness for this data. Show all steps of calculation.

Calculate and then sk.

b. Calculate Software Skewness for this data. Show all steps of calculation. You need to fill the following table after calculating .

Sk=? (Show all steps of calculation)

c. Calculate Skewness using Excel and copy and paste your results here.

Q4. We roll a dice three times. Calculate following probabilities while showing all steps of calculation:

a. What is the probability that we see 6 at all rolls?

b. What is the probability that we see 6 at the first roll and no 6 6 at the remaining rolls?

c. What is the probability that we see at least one 6 while rolling the dice 3 times?

Q5. A CPA (Certified Public Accountant) studied the number of exemptions claimed on tax returns. The data is summarized in the following table:

a. What is the mean number of exemptions claimed? (Show all steps of calculation and use the formula : you can use the direct formulation or tables)

b. What is the variance of the number of exemptions claimed? (Show all steps of calculation and use the formula : you can use the direct formulation or tables)

Q6. A study of the checkout lines at Safeway supermarket revealed that between 4 pm and 7 pm on weekdays, there is average of 4 customers waiting in a line. Assume you are a manager in the supermarket and you are observing that line in that given period; calculate the following by showing all steps of calculation:

a. No customer is waiting in the line!

b. Totally 4 customers are waiting in the line!

c. In total, 4 or fewer (at most 4) customers are waiting in the line!

d. In total, 4 or more (at least 4) customers are waiting in the line!