HELP! - Did I get this 1/2 maths question right?

[geminii]

Okay so here is the question I'm attempting to solve:

Emily walked 12km from Town A to Town B. When she got to Town B, she realised she could have gotten there 6 minutes earlier, had she gone 1km/h faster.
Find her average speed to one decimal point.

So this is how I solved it - or at least attempted to.

Original speed = 12/x
'What she could have gone' speed = 12/(x+1)

Solving...:

12/x = 12/(x+1) + 1/10
12/x - 12/(x+1) = 1/10
12x+12-12x/(x2+x) = 1/10
12/(x2+x) = 1/10
120 = x2+x
x2+x-120 = 0

Then I used the calculator. It gave me this (after I rounded up/down the decimals):
(x+11.5)(x-10.5)
Therefore x = -11.5 or 10.5
Therefore Emily's average speed was 10.5 km/h.


Did I complete this correctly? Please let me know ASAP. Thanks heaps!!!

[Zealous]

Yep, your answer is correct. Well, that's what I got also. I would've done it somehting like this:

Let v=original speed and t=original time.





Now you can solve these two equations using your preferred simultaneous method and you get t=1.1 and v=10.5. Your working is fine and looks at the speed while mine looks at the distance.