Question!! Help me please.....

[Kronos]

Car averages 10mph from point A to point B. If they average B mph on the way back whats the average speed for the entire trip?

Also What do they have to do from B to A to get a total of 15 mph.

 

[JonnyDuke]

Need more input...

 

[ATLien247]

20MPH?

 

[Kronos]

Car averages 10mph from point A to point B. If they average X mph on the way back (B to A). Whats the average speed for the entire trip?

Also, what does the car have to average to get a overall average of 15 mph from B to A?



sorry was confused. suppose to be an X.

 

[IceBlue]

1) (10 + return mph) / 2

2) (10 + 20 ) / 2 = 15, so 20 mph is your answer

This is assuming that the 1st trip is the same route/distance as the return trip.

-Ice

 

[fishlet]

Easy question.
(1)
Let's assume x miles from A to B.
Then needs x/10 hours from point A to point B,
needs x/B hours from point B to point A.
So spent (x/10 + x/B) hours from point A to B.

Drove 2*x miles. (A-> B->A, round trip)

So the AVG speed is 2*x / (x/10 + x/B) = 2 / (0.1 + 1/B)

Use a calculator, you will get your answer.

(2) If the AVG speed is 15mph, then 15 = 2/(0.1 + 1/B),
so the speed from point B to point A = 30mph.


))

 

[superkeith]

<-- agrees with the fish

it's not just a simple average...time and distance, baby. time and distance.

 

[fishlet]

Thanks, superkeith.

 

[IceBlue]

<smacks me forehead> DOH!