How would you calculate this?

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Caporegime
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Time for another GCSE maths question :D

Let's see what you guys come up with. I've already calculated my answer but I think I've done it very differently to what's expected of me so I'm intrigued to see how you guys would do it!

Johannes drove for 3 hours at 50 miles per hour, and for 2 hours at 60 miles per hour.

Find the average speed for the whole journey, giving your answer in SI units.
Click to expand...


I came up with 54mph simply by adding the distance travelled during each hour then dividing it by the amount of hours travelled, as the hour is a constant.

So, what's up GD? :D
 
I don't know what SI units are, but I got 54 mph

Firstly work out the distance travelled at each speed
3*50=150
2*60=120

Total travelled is 270 miles

150+120=270

divide the total miles travelled by the total time drove.

270/5=54mph
 
Last edited:
reilly said:
I don't know what SI units are, but I got 54 mph

Firstly work out the distance travelled at year speed
3*50=150
2*60=120

Total travelled is 270 miles

150+120=270

divide the total miles travelled by the total time drove.

270/5=54mph
Click to expand...

That's what I got and how I done it, I have no idea what an SI unit is either.
 
That's exactly how I worked it out too. Thing is, there's this line at the end of the question:

Answer the question, giving your answer to a suitable number of significant figures and explaining your choice of significant figures.
Click to expand...



Wut? :confused:
 
International System of Units
noun
plural noun: SI units
a system of physical units ( SI units ) based on the metre, kilogram, second, ampere, kelvin, candela, and mole, together with a set of prefixes to indicate multiplication or division by a power of ten.


seems like they want it in Km per hour, which = 87kph or 87,000 in metre's
 
Ah ****, that's just cost me a few points then :(


Ah well, this is just a small part of the assignment anyway. Perhaps I should read the whole thing before hitting submit :p
 
Working out the average speed from 2 numbers is hardly worthy of a GCSE Maths question. Its the SI unit bit is the main test of the question.

StriderX said:
Why the hell is anyone required to know imperial units in the 21st century, honestly...
Click to expand...

Because speed in the UK is most often stated in mph.
 
Hey, this is the first assignment, give it a rest :D


(I may have left out most of my studying and am now playing catch up. Probably)
 
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