Horses For Fun

[kuiperbelt]

A man buys a horse for £70. He then sells the horse for £80. He then buys back the horse for £90. Once again he sells the horse for £100. How much did the man make or lose? Or did he break even?

[ClareTG0ld]

I absolutely agree that doing past papers is the best prep, especially in the circumstances you described. I suppose my point, or worry, is that seeing perfectly laid-out "attacks" means that he's missing out on seeing the vital first step to any problem: what to do when you don't know what to do.

It is, I confess, hard for me sometimes to lay that out in problems where I sort of scan over the diagram, see more or less instantly what to do, and then the remaining steps click into place more or less automatically; but, then at least part of the reason that happens is because I've had years or decades of extra practice, both in solving these problems and in helping others to.

It's that angle that leads me to ask after what working, if any, your grandson is doing for these problems. I'd want to see his thinking process, etc, and try as best I can to communicate mine. In most of these problems, the basic tip is:

1. look for triangles.
2. If there are no triangles, draw them in anyway.
3. Repeat until you find a useful one (ie, one where you know any three things out of the three sides/angles; ideally at least one side, but as other posters have shown, similar triangles also can

[ClareTG0ld]

similar triangles also can be useful, as I was about to finish.

Best of luck to him, anyway, but I am -- within reason -- happy to offer any extra help beyond what's being asked at the moment.

[kuiperbelt]

Thank you Clare!!