SOLUTIONS TO HW 9: Chapter 14

1.

Score	10	50	60	70	80	100
Frequency	1	3	7	6	5	2

2. Pesky pictures...

3. (a)

Grade	Frequency	Percentage
F	1	4.17%
D	3	12.5%
C	7	29.17%
B	6	25%
A	7	29.17%

(b) See the back of the book...

4. Imagine a pie chart representing the percentages above. mmm...pie.

11. (a) N=2+5+6+4+4+5+3+1=30

(b) 0%

(c) (4+4+5+3+1)/30=56.67%

26. (a) Ave=1.5, median=1.5

(b) Ave=2.5, median=2.5

(c) Ave=3, median=3

27.

(a) Ave= (1+2+3+...+98+99)/99 = [(99*100)/2]/99 =50

(b) The locator for the median is L=0.50*99=49.2 Hence, the median is the 50th number. That means the median is 50.

30.

(a) Ave= (25*2+27*7+28*6+29*9+30*15+31*12+32*9+33*9+37*6+39*4)/(2+7+6+9+15+12+9+9+6+4 = 31.05

(b) Locator L=0.5*79=39.5, so the median is the 40th age which is 31.

34. (a) Q1=-5.9

(b) Q3=8.3

(c) Q1=-7.3, Q3=8.3

57. (a) about 2.87

(b) about 2.87

(c) about 2.87

68. The lowest possible score on the first exam is when all the rest of the scores are as high as possible:

(x+100+100+100+200)/6 = 93

x=558-500=58

72. (a) The ten numbers add up to 75. Since min=3, the remaining 9 numbers add up to 72. The smallest possible value of max=8 (it occurs when all the other nine numbers are 8 too).

(b) The largest max=48 (it happens when the first 9 numbers are all 3)

77. (a) male: 10%, female: 20%

(b) male: 80%, female: 90%

(c) The figures for both schools were combined. A total of 820 males were admitted out of a total of 1200 that applied-an admissions rate of 68.3%. Similarly for the women the total admission rate was 51.1%.

(d) Most of the women applied to the school that was harder to get into. So the overall % of women admitted was lower than for the males who applied to the school that admitted most of its applicants.

80. For any data set, the average(A) will be between the Min # and the Max #. Also, for any number, x, in the set, (x-A)^2 < (range)^2 .

Thus the SD= sq root of the average of all (x-A)^2 < sq root of (range)^2 = Range.