Basic Mathematics for College Students

624 Chapter 7 Summary and Review

When did the popularity of snowboarding seem to peak?

The years with the highest participation were 2003 and 2004.

Between which two years was there the greatest decrease in the

number of snowboarding participants?

The line segment with the greatest “fall” as we read left to right is

the segment connecting the data points for the years 2005 and

2006. Thus, the greatest decrease in the number of snowboarding
      participants occurred between 2005 and 2006.

Two quantities that are changing with time can

be compared by drawing both lines on the same

graph.

SKATEBOARDING Refer to the line graphs below that show the

results of a skateboarding race.

Observations:

• Since the red graph is well above the blue graph at time A,
  skateboarder 1 was well ahead of skateboarder 2 at that stage
  of the race.


• Since the red graph is horizontal from time A to time B,
  skateboarder 1 had stopped.


• Since the blue graph crosses the red graph at time B, at that
  instant, the skateboarders are tied for the lead.


• Since the blue graph crosses the dashed finish line at time C,
  which is sooner than time D, skateboarder 2 won the race.

A

Start

Distance traveled

Finish

B C D

Skateboarder 1

Skateboarder 2

A histogramis a bar graph with these features:

1. The bars of the histogram touch.


2. Data values never fall at the edge of a
   bar.


3. The widths of the bars are equal and
   represent a range of values.

SLEEP A group of parents of

junior high students were

surveyed and asked to estimate

the number of hours that their

children slept each night. The

results are displayed in the

histogram to the right. How

many children sleep 6 to 9 hours

a night?

The bar with edges 5.5 and 7.5 corresponds to the 6 to 7 hour range. The

height of that bar indicates that 42 children sleep 6 to 7 hours. The bar

with edges 7.5 and 9.5 corresponds to the 8 to 9 hour range. The height

of that bar indicates that 93 children sleep 8 to 9 hours. The total

number of children sleeping 6 to 9 hours is found using addition:

42 + 93 = 135

135 of the junior high children sleep 6 to 9 hours a night.

20

3.5 5.5 7.5 9.5

Hours of sleep

11.5

40

60

80

Frequency

100

120

15

42

93

50