Chapter 9.1, Problem 57PPS

a.

To determine

Write an expression.

Answer to Problem 57PPS

The expression is $\frac{\text{2miles}}{\text{1track}}\cdot \frac{\text{5280feet}}{\text{1mile}}\cdot \frac{\text{1car}}{\text{75feet}}\cdot \text{5tracks}$ .

Explanation of Solution

Calculation:

From the given:

There are 5 tracks that are each 2 miles long and every mile 5280feet.Each car takes up 75feet.

  $=\frac{\text{2miles}}{\text{1track}}\cdot \frac{\text{5280feet}}{\text{1mile}}\cdot \frac{\text{1car}}{\text{75feet}}\cdot \text{5tracks}$

Thus, the expression is $\frac{\text{2miles}}{\text{1track}}\cdot \frac{\text{5280feet}}{\text{1mile}}\cdot \frac{\text{1car}}{\text{75feet}}\cdot \text{5tracks}$ .

b.

To determine

How many trains’ cars are involved in the backup.

Answer to Problem 57PPS

The $\text{704}$ trains’ cars are involved in the backup.

Explanation of Solution

Calculation:

From the above part (a):

  $=\frac{\text{2miles}}{\text{1track}}\cdot \frac{\text{5280feet}}{\text{1mile}}\cdot \frac{\text{1car}}{\text{75feet}}\cdot \text{5tracks}$

  $\begin{array}{l}=\frac{\text{52800}}{\text{75}}\text{feet Multiply}\\ =\text{704 Simplify}\end{array}$

Thus, $\text{704}$ trains’ cars are involved in the backup.

c.

To determine

How many hours will it take for all the vehicles in the backup to text.

Answer to Problem 57PPS

Hence the $70.4\text{hours}$ many hours will it take for all the vehicles in the backup to text.

Explanation of Solution

Calculation:

From the given:

There are 8 attendants that take 45seconds to check each of the 704 cars.

  $\begin{array}{l}=8\cdot 45\cdot 704\text{seconds}\\ =253,440\text{seconds Multiply}\\ =4224\text{minutes divided by }60\text{ to convert to minutes}\\ =70.4\text{hours divided by }60\text{ to convert to hours}\end{array}$

Thus, the $70.4\text{hours}$ many hours will it take for all the vehicles in the backup to text.