Lesson Finding travel time and average rate

This Lesson (Finding travel time and average rate) was created by by ikleyn(52817)

: View Source, Show
About ikleyn:

Finding travel time and average rate

Problem 1

Every day, Betty travels 25 km from her apartment to the office.
She travels 20 kilometers by car at 40 km/h, parks at the car park, and then walks at 5 km/h
the rest of the way to work. If Betty leaves her home at 6:30 a.m., at what time does she arrive at work?

Solution

Betty travels by car   =  of an hour, or 30 minutes.

After that, Betty walks   = 1 hour to the office.

Hence, Betty spends 1 hours and 30 minutes to get the office. 

If Betsy leaves her home at 6:30 am, she gets the office at 8:00 am.    ANSWER

Problem 2

A delivery van traveled 20 miles at an average speed of 50 miles per hour.
Then it traveled 10 miles at the average speed of 20 miles per hour.
Find the travel time of the whole trip.

Solution

Travel time at the speed of 50 mph  is   =  of an hour, or 24 minutes.

Travel time at the speed of 20 mph  is   =  of an hour, or 30 minutes.

The total travel time of the whole trip is 24 + 30 = 54 minutes.    ANSWER

Problem 3

A boat travels 15 km/h in still water. This boat goes 10 kilometers upstream in a river,
which has the current rate of 5 km/h, and then returns back downstream to its starting point.
(a) What is the travel time for the whole trip in?
(b) what is the average rate of the whole trip?

Solution

The boat's own speed in still water  is 15 km/h.

The boat' rate   upstream is 15-5 = 10 km/h.  Hence, the time traveling upstream is   = 1 hour.

The boat' rate downstream is 15+5 = 20 km/h.  Hence, the time traveling upstream is   = 1/2 hour.

Hence, the total travel time of the whole trip is 1 +  = 1  hours.


The average rate is  the total distance 10 + 10 = 20 km, divided by the total time  

     =  =  = 13 miles per hour..


ANSWER.  The total travel time of the whole trip is 1  hours.

         The average rate of the whole trip is 13 mph.

My other lessons on arithmetic word problems in this site are
    Arithmetic word problems to solve them MENTALLY
    Solving arithmetic word problems by reasoning
    Simple arithmetic word problems solved in a right way
    Arithmetic coin problems
    Simple arithmetic word problems on "rate of work"
    Simple and simplest arithmetic Travel & Distance problems
    Typical arithmetic Travel & Distance problems
    Entertaining catching up arithmetic Travel & Distance problems
    Other basic arithmetic Travel & Distance problems
    Advanced arithmetic word problems on Travel & Distance
    Flying back and forth

    OVERVIEW of the first group of lessons on arithmetic word problems

To see the whole list of lessons on arithmetic problems, use this link Arithmetic problems - YOUR ONLINE TEXTBOOK
It is your way to the entry page of the online textbook on Arithmetic problems.

This lesson has been accessed 550 times.