#### Solved Examples and Worksheet for Reading and Interpreting Scatter plots

Q1The scatter plot displays Andrew's height over a few years. What was Andrew's height when he was 15 years old?

A. 4 ft
B. 5.6 ft
C. 3.5 ft
D. 5 ft

Step: 1
The vertical coordinate of each point in the scatterplot represents Andrew's height and the horizontal coordinate represents his age.
Step: 2
From the graph, the vertical coordinate of the point corresponding to 15 years is 5 ft.
Step: 3
So, Andrew was 5 ft tall when he was 15 years old.
Correct Answer is :   5 ft
Q2The following scatter plot represents the distance traveled by Diane during each hour of her journey. Find the distance traveled by her in 3 hours.

A. 157.5 km
B. 55 km
C. 52.5 km
D. 160 km

Step: 1
The vertical coordinate of each point on the scatter plot indicates the distance traveled by Diane during each hour.
Step: 2
The distance traveled in the first hour of the journey is 50 km.
Step: 3
The distance traveled in the second hour is 55 km.
Step: 4
The distance covered in third hour is 52.5 km. as it is in between 50 and 55.
Step: 5
The total distance covered in the first three hours of the journey = 50 + 55 + 52.5 = 157.5 km.
Step: 6
The distance traveled by Diane in 3 hours is 157.5 km.
Correct Answer is :   157.5 km
Q3The cost of crude oil per barrel over a span of 5 years is represented in the scatter plot. What was the price of crude oil in the year 1998?

A. $30 B.$23
C. $25 D.$29

Step: 1
In the scatterplot, the horizontal axis represents the year and the vertical axis represents the cost per barrel (in $). Step: 2 The height of each point on the scatterplot represents the cost per barrel (in$) of crude oil in the corresponding year.
Step: 3
From the graph, the vertical coordinate of the point corresponding to the year 1998 is 25.
Step: 4
So, the cost of crude oil per barrel in 1998 was $25. Correct Answer is :$25
Q4The cost of crude oil per barrel over a period of 5 years is represented in the scatter plot. In which year was the cost of crude oil per barrel minimum?

A. 1997
B. 1996
C. 1998
D. 2000

Step: 1
In the scatter plot, the horizontal axis represents the year and the vertical axis represents the cost per barrel (in $). Step: 2 From the graph, the minimum cost of crude oil per barrel is$20.
Step: 3
From the graph, the horizontal coordinate corresponding to $20 is 1996. Step: 4 So, the cost of crude oil per barrel is minimum in the year 1996. Correct Answer is : 1996 Q5The scatter plot shows the number of matches won by teams representing the USA in a particular sport from 1986 to 1990. Find the total number of matches won by teams from the USA from 1987 to 1990. A. 195 B. 150 C. 215 D. 172 Step: 1 Number of matches won in 1987 = 35 Step: 2 Number of matches won in 1988 = 70 Step: 3 Number of matches won in 1989 = 45 Step: 4 Number of matches won in 1990 = 65 Step: 5 Total number of matches won by the USA from 1987 to 1990 = 35 + 70 + 45 + 65 = 215 Step: 6 So, the total number of matches won by the USA from 1987 to 1990 = 215. Correct Answer is : 215 Q6The scatter plot represents the number of items of different costs purchased by Lindsay in a supermarket. What is the total amount spent by her in the supermarket? A.$50
B. $90 C.$80
D. $100 Step: 1 The height of each point on the scatter plot indicates the number of items of a particular cost bought by Lindsay. Step: 2 From the graph, the number of items of costs$2, $4,$6, $8 and$10 are 3, 5, 3, 2 and 3 respectively.
Step: 3
The total amount spent by her is the sum of the products of the number of items and the cost of each item.
Step: 4
So, the total amount = $2 x 3 +$4 x 5 + $6 x 3 +$8 x 2 + $10 x 3 = 6 + 20 + 18 + 16 + 30 =$90
[Multiply number of items and cost of each item and add all.]
Step: 5
So, Lindsay spent $90 in the supermarket. Correct Answer is :$90
Q7The scatter plot shows the population of Alabama and California from 1998 through 2002. Which state has a higher population in the year 2000?

A. Alabama
B. California

Step: 1
The height of each point in the plot represents the population of a particular state in a particular year.
Step: 2
From the plot, the population of Alabama in the year 2000 is 2 million.
Step: 3
The population of California in the year 2000 is 8 million.
Step: 4
So, the population of California is higher than the population of Alabama in the year 2000.
[8 million is greater than 2 million.]
Q8The scatter plot shows the number of teachers hired each year from 1980 through 1984. How many more teachers were hired in the year 1983 than those in 1984?

A. 20
B. 15
C. 5
D. 10

Step: 1
The height of each point in the scatter plot represents the number of teachers hired that year.
Step: 2
Number of teachers hired in the year 1983 = 410
Step: 3
Number of teachers hired in the year 1984 = 405
Step: 4
The difference between the number of teachers hired in 1983 and in 1984 = number of teachers hired in 1983 - number of teachers hired in 1984
= 410 - 405 = 5
[Substitute the values and simplify.]
Step: 5
So, 5 more teachers were hired in 1983 than the number of teachers hired in 1984.
Q9The scatter plot shows the number of students and the number of hours they work everyday. How many students work four hours a day?

A. 40
B. 50
C. 20
D. 30

Step: 1
The height of each point in the scatter plot represents the number of working hours and the number of students working.
Step: 2
From the graph, the height of the point representing those who work 4 hours a day corresponds to the working hours of 30 students.
Step: 3
So, the number of students who work for 4 hours everyday is 30.
Q10The scatter plot represents the requirement of Vitamin D by a person at various stages in his or her life. Find the number of milligrams of Vitamin D that a 50 year old person requires.

A. 14
B. 6
C. 2
D. 10

Step: 1
The height of each point in the scatter plot represents the number of milligrams required at that particular age.
Step: 2
From the scatter plot, the height of the point corresponding to the age of the person when he or she is 50 is 10 mg.
Step: 3
So, 10 milligrams of vitamin D is required for a 50 year old person.
Q11A wholesale dealer of stationery products plots the following scatter diagram to represent his income from the year 1985 to 2000. In which year was his income the highest?

A. 2000
B. 1990
C. 1995
D. 1985

Step: 1
The height of each point in the graph indicates the income (in $1000) of the dealer in the particular year. Step: 2 From the graph, the incomes of the dealer in 1985, 1990, 1995 and 2000 are$40000, $45000,$35000 and \$50000, respectively.
Step: 3
The income of the dealer was the highest in 2000.
Q12From the scatter plot, what is the decrease in the consumption of goods from the year 1999 to 2000?

A. 25
B. 10
C. 35
D. 30

Step: 1
From the plot the consumption of the goods in 1999 was 35 million tons.
Step: 2
The consumption of the goods in the year 2000 is 25 million tons.
Step: 3
So, the decrease in the consumption of goods is 35 - 25 = 10 million tons.
Q13The scatter plot shows the time it takes Annie to reach City B from City A at different speeds. How much time will be saved if Annie travels at a speed of 60 miles per hour than that if she travels at 40 miles per hour ?

A. 8 minutes
B. 7 minutes
C. 5 minutes
D. 4 minutes

Step: 1
Each point in the scatter plot represents the time taken to travel from City A to City B, at various speeds.
Step: 2
From the graph, the time taken by Annie at a speed of 40 miles per hour is 15 minutes.
Step: 3
The time taken by her at a speed of 60 miles per hour is 10 minutes.
Step: 4
Difference between the times = 15 - 10 = 5 minutes
Step: 5
So, Annie can save 5 minutes by traveling at a speed of 60 miles per hour than at a speed of 40 miles per hour.
Correct Answer is :   5 minutes
Q14The scatter plot shows the population of Alabama and California from 1998 through 2002. By what percent did the population of Alabama increase from 1999 to 2002?

A. 200%
B. 100%
C. 50%
D. 150%

Step: 1
The height of each point in the plot represents the population of a particular state in a particular year.
Step: 2
From the plot, the population of Alabama in the year 1999 is 4 million.
Step: 3
The population of Alabama in the year 2002 is 8 million.
Step: 4
Increase in the population = 8 - 4 = 4 million
[Subtract 4 from 8.]
Step: 5
So, the percentage increase in the population = IncreaseOriginal x 100
= 44 x 100 = 100%
[Divide.]
Q15The scatter plot displays the weight of Charles as he grew older. What was his weight when he was 30 years old?

A. 100
B. 125
C. 50
D. 175

Step: 1
In the scatter plot, the horizontal axis represents Charles's age and the vertical axis represents his weight in lb.
Step: 2
The vertical distance of each point in the scatter plot indicates the weight of Charles when he was a particular age.
Step: 3
From the graph, the vertical distance of the point corresponding to 30 is 125.
Step: 4
So, the weight of Charles was 125 lb when he was 30 years old.