Question

When truckers are on long-haul drives, their driving logs must reflect their average speed. Average speed is the total distance driven divided by the total time spent driving. A trucker drove 3 hours on a freeway at 60 miles per hour and then drove 20 miles in the city. The trucker’s average speed was 57.14 miles per hour.
a. Write an equation that models the situation.
b. How long was the trucker driving in the city to the nearest hundredth of an hour?

Answer 1

0.500 hour is the answer

Answer 2

Answer:

0.500 hour

Step-by-step explanation:

Givens

Distance

• Total Distance on the highway = 3hr * 60 miles / hr = 180 miles
• Distance in the city = 20 miles
• Total Distance = 180 + 20 = 200 miles

Time

• Time on the highway = 3 hours
• Time in the city = x

Formula

d /t = r

Solution

• Average rate = 57.14
• Total Distance / Total Time = average rate
• 200 / (3 + x) = 57.14                               Multiply both sides by 3 + x
• 200 = 57.14 * (3 + x)                               Remove the brackets
• 200 = 57.14*3 + 57.14x                           Multiply the factors on the right
• 200 = 171.42 + 57.14x                              Subtract 171.42 from both sides.
• 200 - 171.42 = 171.42 - 171.42 + 57.14x   So the subtraction
• 28.58 = 57.14x                                         Divide by 57.14
• 28.57/57.14 = x
• x = 0.500 hour                                        Answer