PROBLEMS ON ANALYZING DOT PLOTS

Problem 1 :

Students in a third grade class were asked to name their favorite color. The data from the survey is shown below.

Which statement is true based on the information shown on the dot plot ?

a) The number of of students that chose blue is greater than the total number of students that chose green, white and yellow.

b) The total number of students that chose red, white and blue is 20.

c) The number of students that chose black is the same as the total number of students that chose green and white.

d)  The number of students that chose red is greater than the total number of students that chose green and yellow.

Solution :

Option a :

number of of students that chose blue > number of students that chose green, white and yellow.

5 > 3 + 2 + 3

5 > 8

False

Option b :

number of students that chose red, white and blue is 20.

5 + 2 + 5 = 20

12 = 20

False

Option c :

number of students that chose black = number of students that chose green and white.

5 = 3 + 2

5 = 5

True

So, option c is correct.

Problem 2 :

The data from a survey of 12 students shows how many video games they rented during the past month,

Which statement is not true based on the data shown in the dot plot?

a) The total number of video games rented by 4 students last month is 3.

b) The total number of students that rented 5 or 6 video games last month is 6.

c)  The total number of video games rented by 1 student is 15.

d)  The total number of students that rented 2, 3, or 10 video games is 3.

Solution :

Option a : 

The total number of video games rented by 4 students last month = 3.

From the above dot plot,

Total number of video games rented = 1 + 1 + 3 + 4 + 2

= 11

So, option a is incorrect.

Option b :

The total number of students that rented 5 or 6 video games last month is 6.

number of students that rented 5 or 6 = 4 + 2

= 6

It is true.

Problem 3 :

The data from a survey of 15 students shows estimates for the number of hours of television they watch each week.

Which statement is true based on the data shown on the dot plot ?

a) the total number of televisions watched by 11, 12 and 14 students is greater than the total number of hours watched by 5, 10, 15 and 20 students.

b) More students watched 11 or 12 hours of television than watched 16 of 17 hours.

c)  The total number of students that watched 5, 10, 15 and 20 hours is equal to the total number of students watched 11, 12, 14, 16 and 17 hours is equal.

d) None of these

Solution :

Option a :

Total number of televisions watched by 11, 12 and 14 students > total number of hours watched by 5, 10, 15 and 20 students.

1 + 2 + 3 > 1 + 2 + 2

6 > 5

True.

So, option a is correct.

Problem 4 :

The data shows the numbers of different sizes of shirt ordered for a school choir.

Which statement is true based on the data shown on the dot plot ?

a)  The number of shirts ordered in size 10 is greater than the total number of shirts ordered in size 4, size 5 and size 7.

b) the total number of shirts ordered in size 10 and size 12 is 15.

c) The total number of shirts ordered in size 7 and size 14 is greater than the number of shirts ordered in size 10.

d)  The total number of shirts ordered in size 5 and size 14 is equal to the number of shirts ordered is size 10.

Solution :

Option a: 

7 > 1 + 4 + 3

7 > 8

So, option a is false.

Option b :

= 7 + 6

= 13

Option b is false.

Option c :

 3 + 3 > 7

6 > 7

Option c is incorrect.

Problem 5 :

Twenty third grade students were asked how many pets their family has. The dot plot shows the data

How many more of the student's families have 1 pet than have 4, 5 or 6 pets ?

a)  6    b)  4   c)  2    d) 1

Solution :

Number of families has 1 pet = 6

Number of families has 4, 5 or 6 pets = 2 + 1 + 1

= 4

Difference = 6 - 4

= 2

So, option c is correct.