STA 2023 Practice TEST 1

1) (3 points)A fitness club surveys 40 randomly selected members & finds the average

weight of those questioned is 157 pounds. Is this value a parameter or a statistic?

________________________

2) (2 points each) Tell if the value is continuous or discrete.

a) number of stories in a building ________________________

b) height of a tree in feet ________________________

3) a) (2 pts.) A marketing firm surveys 100 people to see how many use a certain product

& 15 say they do.

Is this study observational or experimental? ________________________

b) (2 pts.)A professor gives one class a practice test and compares actual test grades

to a class that does not get the practice test.

Is this study observational or experimental? ________________________

4) (2 pts. Each) Identify the BEST level of measurement for each: ratio, interval, ordinal

or nominal.

a) amount of fat in grams in cookies. _________________________

b) subjects in which college students major _________________________

For # 5 – 14, use this sample list of quiz scores & you may use your calculator to help in any way. Round answers to nearest tenth.

3 6 8 9 10 11 11 13 13 14 14 15

15 15 16 16 16 17 18 20

.

5) (3 points) Find the mean ________________________

6) (3 pts.) Find the median. ________________________

7) (3 pts.) Find the mode(s), if any. ________________________

8) (3 pts.) Find the range. ________________________

9)(2 pts. Ea.) a) Find Q₁ . ________________________

b) Find Q₃. ________________________

10) (4 pts) Find the extremes. ________________________

11) (3 pts.) Find the standard deviation _______________________

12) (3 points) Find the variance. _______________________

13) Find the z-score for data value 18. (round to 2 places) ______________________

(3 points)

14) Is the data value 18 unusual or not unusual? _______________________

(3 points)

15) Use your calculator to make a box-plot and copy it here. (4 points)

For #16 & 17, z is a STANDARD normal distribution.

16) (3 pts) Find the probability that z lies between ( –2.41) and 1.63.

(Round to 4 decimal places.) ________________________

17) Find P(z < 1.13) (Round to 4 places.) (3 pts) ______________________

18) Scores on a test are normally distributed with a mean of 78.5 and standard deviation

of 7.9. Find the score which is the 80^th percentile. (round to the appropriate whole

number.) (3 pts)

______________________

19) The time it takes a mechanic to re-build the transmission of a 1992 Chevy shows

the mean is 8.4 hours and standard deviation is 1.8 hours. If a mechanic is

randomly chosen, find the probability that his re-build time exceeds 9.1 hours.

(Round to 4 decimal places.)

20) According to the Empirical Rule, what percentage of values in a normal distribution

will be within two standard deviations of the mean? (3 pts)

_________________________

21) (10 points)

Use the following set of paired data to fill in the blanks. Test using a = .05.

x 5 10 4 6 10 9

y 64 86 69 86 59 87

Draw your test here: Test for Linear correlation:

H₀ : ____________________

-1 0 1 H_a : ____________________

Critical value: ________________

Calculated value:______________

Reject H₀ or Fail to reject H₀ ?

____________________________

Significant correlation? _________

(“yes” or “no”)

Equation of the Regression Line: (values rounded to the nearest thousandth.)

____________________________

Predict y when x = 8 (to the nearest whole number.) _________________________

22) (10 points)

Use the following set of paired data to fill in the blanks. Test using a = .01.

x 23 25 28 21 21 25 26 30 34 36

y 49 53 59 42 47 53 55 63 67 75

Draw your test here: Test for Linear Correlation:

H₀ :________________________

H_a :________________________

-1 0 1 Critical value:________________

Calculated value:_____________

Reject H₀ or Fail to reject H₀ ?

__________________________

Significant correlation? _______

(“yes” or “no”)

Equation of the Regression Line: (values to the nearest tenth.)____________________

Predict y when x = 29 (to the nearest whole number.)___________________________

23) (2 points each) 5000 students were surveyed to see what degree they are seeking and

the results are in this pie chart.

a) What program has the most students?

b) How many students are taking Personal Interest courses?

c) How many degrees of the circle for A.A. degree?

24) (2 points each) Use this histogram that follows to answer the questions below.

a) How many scored 17 to 20?

b) What is the relative frequency for the class (category) 17 to 20?

c) What is the class midpoint of the class (category) 17 to 20?

d) Is this data more symmetric or skewed?