7th Grade Math

R26 Selected Answers and Solutions

Selected Answers and Solutions

Upper Quartile: The middle number of the top half

of the data is 1,038.

Lower Quartile: The middle number of the lower

half of the data is 513. c. To fi nd the inner quartile

range, subtract the lower quartile from the upper

quartile. 1,038 - 513 or 525. d. To check for

outliers, fi rst multiply the inner quartile range by

1.5: 525 × 1.5 = 787.5. Add 787.5 to 1,038 and

subtract it from 513. No data falls outside this

range, so there are no outliers.

5. ranges 50 and 45; medians both 50; upper
   quartiles both 60; lower quartiles 45 and 35;
   interquartile ranges 15 and 25; Both sets of data have
   the same median while the fi rst set is more spread
   out than the second. 7. median: 357.5, upper
   quartile: 422, lower quartile: 298, interquartile range:
   124 9. median: $24.27, upper quartile: $28.99, lower
   quartile: $19.99, interquartile range: $9.00 q
   1111 Lucy - median: 7, upper quartile: 9, lower
   quartile: 5, interquartile range: 4; Dena – median: 7,
   upper quartile: 9, lower quartile: 6, interquartile
   range: 3; They have the same median and upper
   quartile range, but Lucy′s interquartile range is larger,
   meaning her mileage is more spread out than Dena′s.


6. Sample answer: 6, 30, 33, 41, 45, 71 15. D


7. H 19. Sample answer: The mean price of the
   items listed is $3; however, they are calculating the
   mean price by including the kid’s cone, a low
   priced item.

Pages 506–509 Lesson 9-2B

1a.

246810 12 14 16

1b. 50%

1c. Sample answer: The length of the box-and-whisker

plot shows that the depths of the earthquakes are not

concentrated around a certain depth.

33

35404550556065707580859095100

Step 1 Order the numbers from least to greatest. Then

draw a number line that covers the range of

data. 35, 55, 61, 65, 74, 88, 92, 96, 97, 99, 100

Step 2 Find the median, the extremes, and the upper

and lower quartiles. Mark these points above

the number line. Median: 88; Extremes: 35,

100; UQ: 97; LQ: 61

Step 3 Draw the box so that it includes the quartile

values. Draw a vertical line through the

median value. Extend the whiskers from

each quartile to the extreme data points.

5.

40 45 50 55 60 65 70 75 80

Height of Waves (in.)

7a.

0 100 200 300 400 500 600

Lengths of Coastline (mi)

7b. 25% 7c. 127 mi 7d. Sample answer: The

length of the box-and-whisker plot shows that

the number of miles of coastline for the top 25%

of the states varies greatly. The number of

miles of coastline for the bottom 25% of states is

concentrated.

9. Most fruits have between 50 and 130 Calories of
   food energy, and most vegetables have between 25
   and 110 Calories of food energy. At least one fruit
   has almost 450 Calories of energy and at least one
   vegetable has about 350 Calories of energy. So on
   the whole, the food energy of fruits and vegetables
   does not vary greatly.
   1111 a. Brownsville, TX Caribou, ME

Low: 59 9

High: 85 66

Median: ^75 + 2 76 = 75.5 ^38 + 2 43 = 40.5

Upper

Quartile:^

_^82 +^83

2 = 82.5^

_^54 +^61

2 = 57.5

Lower

Quartile:^

_^62 +^69

2 = 65.5^

_^15 +^25

2 =^20

Brownsville: 59, 85, 75.5, 65.5, 82.5; Caribou: 9, 66,

40.5, 57.5, 20

11b.

0 1020304050

Caribou, ME

Brownsville, TX

60708090

11c. The Brownsville data have a smaller

interquartile range, so the data are more tightly

clustered around the median. The Caribou data are

more spread out. 13. Sample answer: {60, 60, 60,

60, 60, 70, 75, 80, 85, 85, 85, 85}; median = 72.5; LQ =

lower extreme = 60; UQ = upper extreme = 85

15. Sample answer: {28, 30, 52, 68, 90, 92};

30 40 50 60 70 80 90

17. A 19. I 21. range: 12; median: 7; UQ: 9.5; LQ:
    4.5; IQR: 5 23. mean: 5.6; median: 5.5; mode: 2


18. mean: 11.6; median: 11; mode: 10.

R01_R42_EM_SelAns_895130.indd R26 1/18/10 9:51 AM