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# Once: win one of two Mensa Brain Trainer hand held consoles

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this ones a good tester A helicopter covers its outward journey at 322 mph. It returns, over exactly the same distance at 241.5 mph What is the helicopters average speed over the entire journey?… Read More
7y, 10m agoFound 7 years, 10 months ago / ended 30 Sep 0930 September 2009
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win one of two Mensa Brain Trainer hand held consoles
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this ones a good tester

A helicopter covers its outward journey at 322 mph.
It returns, over exactly the same distance at 241.5 mph
What is the helicopters average speed over the entire journey?

For a chance to win one of two Mensa Brain Trainer hand held consoles, simply e-mail the correct answer together with your full name and address to the Puzzle Editor

I make the answer 2*(241.5*322)/(241.5+322) = 276mph.
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7y, 10m agoFound 7 years, 10 months ago / ended 30 Sep 0930 September 2009
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(7)
#1
surely you just add both and then divide by 2?
i make it 281.75
#2
entered, thanks
#3
wow, that took all of 2 seconds.
try this one
If birmingham is 26 miles from your position, burnley is 50 miles, bradford is 8 miles. How far is blackpool?
#4
brooke007bond
Hi, I believe the answer is 281.75
to find the average speed you add the two speeds then divide by two.
322 + 241.5 = 563.5, 563.5 / 2 = 281.75

That's the common mistake people make with this sort of problem. Speed=distance/time (s=d/t). You can rearrange the equation to t=d/s

For the outward journey, the time taken is equal to 322/distance. On the return journey, the time taken is equal to 241.5/distance. This makes the total time of the journey 322/d + 241.5/d. If the total distance travelled on the journey is 2d, the average speed is 2d/[(322/d)+(241.5/100)] = 276mph
#5
Can anyone give me the e'mail address of the Puzzle Editor, my laptop will not open a direct link
#7
Thanks