Chapter 4.6, Problem 18PPS

(a)

To determine

To make: a table showing gallons of gasoline remained in the tank

Answer to Problem 18PPS

Gallons	40	33	26	19	12	5
Hour h	0	1	2	3	4	5

Explanation of Solution

Given:

40 gallons of gasoline in the fuel tank

Each hour, 7 gallons of gasoline is used.

The bus will stop for gas when there are 10 gallons left.

Calculation:

Make a table to show how many gallons of gasoline are remaining in the tank after each hour.

To construct a table,

took the total gallons (40) and subtract 7 gallons for each hour.

Gallons	40	33	26	19	12	5
Hour h	0	1	2	3	4	5

Conclusion:

Therefore, the table is

Gallons	40	33	26	19	12	5
Hour h	0	1	2	3	4	5

(b)

To determine

To find:

Write and solve an equation to find how many hours will pass before the bus will have to stop for gasoline.

Answer to Problem 18PPS

The bus will have to stop for gasoline after 4.3 hours.

Explanation of Solution

Given:

At the start of the school trip to Washington D.C, the tour bus has 40 gallons of gasoline in the fuel tank. Each hour, the bus uses 7 gallons of gasoline. The bus will stop for gas when there are 10 gallons left.

Calculation:

The objective of the problem is to find the equation that satisfies the hypothesis of the problem and solve the obtained equation.

Let h be the number of hours.

The gasoline remains in the tank after h hours is 40-7h.

The bus will stop for gas when there are 10 gallons left.

Find the variable h which satisfies the equation 40-7h =10.

  $\begin{array}{l}40-h=10\\ 40-7h-40=10-40\text{ Subtraction property of equality}\\ -7h=-30\text{ Simplify}\\ \frac{-7h}{-7}=\frac{-30}{-7}\text{ Divide by -7 on both sides}\text{.}\\ h=4.28\text{ Simplify}\\ \approx \text{4}\text{.3}\end{array}$

Therefore, the bus will have to stop for gasoline after 4.3 hours.

Conclusion:

Therefore, the bus will have to stop for gasoline after 4.3 hours.