AP Statistics / Mr. Hansen

Name: __________________________

10/1/2014

Battery bonus (for Mr. Hansen’s use only): ____

 

Test #1 Answer Key

 

1.

(a) Like all statistics, this sample proportion is a number computed from data. However, the long-run relative frequency of heads in the infinite collection of possible coin flips cannot be computed, although we can estimate the value of that parameter.

 

(b) a parameter

 

2.

(a) p
(b) No

 

3.

“LOOK AT YOUR DATA!”

 

4.

(a) how the values change over time
(b) stemplots

 

5.

(a) categorical
(b) pie
(c) bar

 

6.

(a) right
(b) greater

 

7.

(a) normal
(b) bimodal

 

8.

run a controlled experiment

 

9.

(a) 0.5, 1.1, 2, 2.5, 2.5
    71, 76, 81, 87.5, 93
(b)  = 1.77 hrs./night [1.8 is acceptable; units are desirable, but no penalty if omitted here]
(c) s = 6.6 dB [units may be omitted here without penalty]
(d) [checked in class]
(e) The center (median) is about 81 dB. The data show right skewness, with no notable gaps or outliers. The IQR is about 11.5 dB, and the range is 22 dB. Since the IQR is small relative to the median, we can say that the data are fairly compressed. [Less thorough answers that clearly speak to center, shape, and spread of the distribution are also acceptable. Also, be aware that a 22 dB range, while not excessively large in terms of human hearing perception, represents a factor of about 150 in terms of power levels.]
(f) [Almost everyone got all the points here. The x-axis must be marked with at least 2 numeric values and the caption “HW (hrs./night).” The y-axis must be marked with at least 2 numeric values and the caption “Whininess (dB).” Note: The y-axis caption should read from bottom to top. However, there is no penalty if you oriented it from top to bottom.]
(g) negative
(h) Larger values of HW are associated with generally smaller values of whininess, and vice versa. [Note: There is a point penalty if you wrote anything about larger values of HW “causing” generally smaller values of whininess.]
(i) 90 dB [any answer in the upper 80s is also acceptable]
(j) Insufficient information [not an experiment]
(k) Insufficient information [not an experiment]
(l) Yes
(m) Yes [simply read value on the y-axis and follow to x-axis value below]
(n) ; dB2
(o) n = 17; convenience sample

Number the students from 1 to 269, write each number on a uniform slip of paper, mix the numbers up, and draw the desired number of slips from a hat.

Alternate method: Number the students from 1 to 269, associate each number from 1 to 269 with a pseudorandom real number (generated by TI-83/84 or by Excel), and use the column of pseudorandom values as a sort key to reorder the list of 269 integers. Then, choose the desired number of students as the first n values in the newly sorted list. This method provides an SRS.