ILEARN Practice (7th)

A principal wants to know if students at a particular high school are in favor of a new dress code at their school. The principal is not to ask the opinion of every student at the school, so she needs to select an appropriate sample of the students to represent the high school.

Select which sample of students the principal should choose.

• Students randomly selected from a list of all students at the school.

• Students sitting at randomly selected tables in the library.

• Students she selects from the hallway between classes.

• Students selected by teachers.

Answer explanation

We will talk more about this in the next chapters. The other options show bias because they are not random.

Mathematical Equivalence

ON

A bag contains 16 marbles. There are 5 blue, 9 yellow, and 2 red marbles. One marble is selected at random.

True or False: It is impossible that a green marble will be selected.

• True

• False

Answer explanation

since there are no green marbles, it is impossible

A bag contains 16 marbles. There are 5 blue, 9 yellow, and 2 red marbles. One marble is selected at random.

True or False: It is unlikely that a yellow marble will be selected.

• True

• False

Answer explanation

since more than half of the marbles are yellow, it is likely that it will be chosen

A bag contains 16 marbles. There are 5 blue, 9 yellow, and 2 red marbles. One marble is selected at random.

True or False: It is certain that a blue marble will be selected.

• True

• False

Answer explanation

since there are colors other than blue, it is not certain that a blue marble will be chosen

A bag contains 16 marbles. There are 5 blue, 9 yellow, and 2 red marbles. One marble is selected at random.

True or False: It is unlikely that a red marble will be selected.

• True

• False

Answer explanation

since less than half of the marbles are red, it is unlikely that it will be chosen.

Mathematical Equivalence

ON

This graph shows a proportional relationship between the number of hours a factory is in operation and the number of gallons of water used. Select true or false for each statement.

1. The factory used 4 gallons of water when it is in operation for 4000 hours. ​ (a)   ​

2. Point W represents the number of gallons of water used when the factory is in operation for 7 hours.​ (b)  

3. The factory uses 9000 gallons of water when it is in operation for 9 hours. ​ (c)  

• False
• True

Answer explanation

1. is false because it should be 4000 gallons for 4 hours.