Stat230 Quiz 1 complete solutions correct answers key

Stat230 Quiz 1 complete solutions correct answers key

You must use the TFE Editor to present your answers. Download the Quiz and post your answers via the Assignment Folder.

For question #1, a typical row for the Stem & Leaf plot might look like 3|0269. Where, the vertical line is obtained by using “Shift & |\” key. The line is inserted at the location of the cursor.

Submit quiz via the Assignment Folder

(15%) 1. A survey of the number of calls received by a sample of Southern Phone Company subscribers last week revealed the following information.

52 43 30 38 30 42 12 46 39 37 34 46 32 18 41 5

a) Develop a stem-and-leaf chart. Ab  ove for tips on presenting Stem-Leaf plot.

 ---------------------------------

                       0 | 5

                     1  | 2,8

                    3   | 0,0,8,9,7,4,2

                     4  | 1,2,3,6,6

                     5  | 2

2.    b)  What basic conclusions can be drawn from this chart?

The chart shows the 30's are the busiest time. The 30's have 7 while all others have less

3.    c)  Compute the 5 number System for this data set and list Xmin,Q1,Q2,Q3 & Xmax. See

Videos and show how the pointer was computed for each quartile.

Xmin=5 xmax=52       Lp = (n+1) X p/100    Q1 (25 percentile) =(16+1)(.25) = 4.25 Q1=4.25

L(50) = (16 +1)(.5) = Q2 = 16.5           L(75)= (16+1)(.75) 12.75 Q3

(15%) 2. For the following table, what is the value of : a) P(A1) b) P(B1│A2) c) P(B2 and A3). Compute this as P(B2)*P(A3│ B2) . Rows are B1 & B2: columns are A1, A2 & A3. What are the values of P(B2) , P(A3|B2) and P(B2&A3)? In what row and column will you find this answer?

Second Event

First Event

A1

A2

A3

Total

B1

2

1

3

6

B2

1

2

1

4

Total

3

3

4

10

A) 2

B

a) 3/10

b)8/10

c1/10

A)P(A1) = 3/10

(15 pnts.) 3. The chart below gives the percentage of counties in the US that use various methods for recording votes in 1980 & 2002. Set up side-by-side bar charts by year using the instruction for Side-By-Side Charts in the Class Notes Conference. Copy/Paste your Chart into the TFE Editor from EXCEL.

METHOD

1980

2002

Punch cards

18.5

15.5

Lever machines

36.7

10.6

Paper ballots

40.7

10.5

Optical scan

0.8

43.0

Electronic

0.2

16.3

Mixed

3.1

4.1

(15 pnts.) 4. The following are a sample of the weights of nine jars of peanut butter.

7.69 7.72 7.80 7.86 7.90 7.94 7.97 8.06 8.09

a) Compute the median weight. b) Compute the standard deviation of the sample using the shortcut formula. Show the formula and values for each term and compute the answer. Use the TFE Equation Editor. c) Compute the 5 Number System for this data. Just list the values as Xmin=xxx, Q1=xxx,Q2=xxxx,Q3=xxxxx, Xmax = xxxx. d) Are there outliers? An outlier value is defined as unusually large or small according to the expressions: Answer yes or no.

Outlier > Q3 + 1.5(Q3-Q1) or, Outlier < Q1-1.5(Q3-Q1)

(15 pnts.) 5. Answer questions a. through f. of 3.23 below.

Show work for part f. only.

(15 pnts.)

6. Compute the mean and standard deviation for the data in the table below. State your assumptions and show all calculations. See Video- Mean & Variance for Grouped Data in Videos –Topics In Stat 230(1) conference.

Distance

Frequency

0 to 5 5 to 10 10 to 15 15 to 20 20 to 25

4 15 27 18 6

(10%) 7. A box contains 3 red balls and 4 green balls. If two balls are randomly selected in sequence, what is the possibility that a red ball and a green ball are picked out of the box. State the rule for P(A&B) and then substitute the values and compute the answer.