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Bernard drove for 6 hours at an average speed of 116 km/h to reach town. For the first 262 km of the journey, he drove at 131 km/h. Find the

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Bernard drove for 6 hours at an average speed of 116 km/h to reach town. For the first 262 km of the journey, he drove at 131 km/h. Find the average speed of the remaining of the journey. (Round off your answer to 1 decimal place)

Guest May 23, 2014

#4
+91436
+5

okay,

Thank you for telling us that you didn't understand - We need your honest feed  back.  Just make sure you think really hard first.  But if you still don't understand - Always say so.

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CPhill's answer is very good but I will try and break it down further.

First look at the whole trip.

6 hours at 116km/hr   will take the car 6*116 = 696km

So the whole trip is 696km and will take 6 hours.

--------------------------------------------------------------

Now I am going to look at the first part of the trip.

You travel 262km at a speed of 131km/hour

It will help if you understand that 131km/1hour is the same as 1hour/131km

That is if you go 131km in an hour then you must take 1 hour to travel 131km.

I want to know how long this part of the journey took.

$$\frac{1hour}{131km}\times\frac{262km}{1}$$

the km cancel out and you are left with     $$\frac{262}{131}hours=2 hours$$

So for this first stretch you travel 262km in 2 hours

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Now you need to know the average speed for the second part of the trip.

speed = distance/time

So you need  distance and time taken.

The whole trip took 6 hours.  The first part took 2 hours.  So the second part must have taketn 6-2=4 ours

I worked out that the whole distance was 696km.  The first part was 262km.  So the second part has to be 696-262=434km

Speed for the second part is 434km/4hours = 108.5Km/hour

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I hope that that helps.

Melody  May 24, 2014
Sort:

#1
+80875
+5

If he drove 6 hrs. at 116km/hr., the total length of the trip was 6hrs * 116km = 696km

And he travels 262km in the first 2 hours. So the distance left to travel in the last four hours was :The total distance traveled (696) -  the distance already traveled (262) = 434km

So, the final 4 hrs Bernard traveled 696 - 262 = 434km

And Distance/Time = Rate......... so

434km/4hrs = 108.5 km/hr

And that's the rate for the rest of the trip.

CPhill  May 23, 2014
#2
+11757
+5

sorry CPhill i actully cant understand ur answer proplerly ! im getting a bit confused ?

rosala  May 23, 2014
#3
+80875
0

What confused you??

CPhill  May 23, 2014
#4
+91436
+5

okay,

Thank you for telling us that you didn't understand - We need your honest feed  back.  Just make sure you think really hard first.  But if you still don't understand - Always say so.

-----------------------------------------------------------------------

CPhill's answer is very good but I will try and break it down further.

First look at the whole trip.

6 hours at 116km/hr   will take the car 6*116 = 696km

So the whole trip is 696km and will take 6 hours.

--------------------------------------------------------------

Now I am going to look at the first part of the trip.

You travel 262km at a speed of 131km/hour

It will help if you understand that 131km/1hour is the same as 1hour/131km

That is if you go 131km in an hour then you must take 1 hour to travel 131km.

I want to know how long this part of the journey took.

$$\frac{1hour}{131km}\times\frac{262km}{1}$$

the km cancel out and you are left with     $$\frac{262}{131}hours=2 hours$$

So for this first stretch you travel 262km in 2 hours

-------------------------------------------------------------------------

Now you need to know the average speed for the second part of the trip.

speed = distance/time

So you need  distance and time taken.

The whole trip took 6 hours.  The first part took 2 hours.  So the second part must have taketn 6-2=4 ours

I worked out that the whole distance was 696km.  The first part was 262km.  So the second part has to be 696-262=434km

Speed for the second part is 434km/4hours = 108.5Km/hour

--------------------------------------------------------------------------

I hope that that helps.

Melody  May 24, 2014

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