Question

Pieter wrote and solved an equation that models the number of hours it takes to dig a well to a level of 72 feet below sea level. 7h – 5(3h – 8) = –72 Which statement is true about Pieter’s solution? 1. It cannot be a fraction or decimal because the depth of the well is a whole number. 2.It must be a positive number since it represents a number of hours. 3. It must be a negative number because the depth is below sea level. 4.It cannot be greater than –72 because that is the depth of the well.

Answer 1

2. It must be a positive number since it represents a number of hours.

Explanation:

He solved it for h, the number of hours, not for the depth which is given as -72, or 72 feet below sea level.

Answer: 2. It must be a positive number since it represents a number of hours.

Answer 2

2. It must be a positive number since it represents a number of hours.

Explanation:

Here, the given equation that models the number of hours it takes to dig a well to a level of 72 feet below sea level,

`7h-5(3h-8)=-72`

Since, here h is a variable,

So, h must represent the number of hours,

Also, after solving the above equation we will get the value of h ( number of hours ),

We know that the number of hours can be in fraction or decimal,

⇒ Option (1) is incorrect.

And, number of hours can not be negative,

⇒ Option (2) is correct.

⇒ Option (3) is incorrect.

Now, a positive number > -72,

⇒ The value of h > -72

⇒ Option (4) is incorrect.