Need help on this one (weighing "rocks")

[lukie13]

Five rocks were weighed on a scale. However, each rock was weighed two at a time, ten times total , so that every possible combination of two rocks were weighed. The scale had the following readouts for the pairs: 236 pounds, 244 pounds, 228 pounds, 250 pounds, 258 pounds, 230 pounds, 246 pounds, 238 pounds, 242 pounds, and 252 pounds. How heavy was the heaviest rock?

Can't really get started...

 

[stapel]

Re: Need help on this one...please

Five rocks were weighed on a scale....

Nice try. But the latest Neopets' "Lenny Conundrum" doesn't say "rocks"; it says "grundos".

This is a math tutoring service, not a Neopets' discussion site. If you want to learn the math, then please reply showing the effort you've made. If you're just wanting the answer to the Lenny, then Google the thing and copy the answer from one the places it was posted yesterday.

Eliz.

 

[lukie13]

I actually do want the help. I haven't done perms and combs since I was in grade 12. The fact that they give absolutely no further numbers kinda throws me. If they suggested that the lightest one weighs 125 it would have been more help. Farthest I have got has been - the heaviest has to be in the 252 & 258 combined weight group; additionally, the lightest has to be in the 228 & 230. I can conclude then that the heaviest has to be six pounds heavier than the next heaviest. That's where I get into a little trouble. thanks

 

[stapel]

I actually do want the help.

This was posted yesterday on one of the "Lenny" sites:

This is a variant of the classic "haybales" or "pumpkins" problem.

. . . . .Ask Dr. Math: Weighing Bales of Hay (1997)

. . . . .Ask Dr. Math: Weighing Bales of Hay (1996)

Note that the weights in this puzzler, in order, are:

. . . . .228, 230, 236, 238, 242, 244, 246, 250, 252, 258

Then follow the methodology of the above (or other) examples.

Other sources include:

. . . . .Math Central: Algebra Weekend Word Problem

. . . . .POW Answer for December 10, 2001

. . . . .Perpelxus: "Pumpkins 2"

. . . . .Math Online: "You have five bales of hay..."

If you get stuck, please reply showing how far you have gotten in following the methology explained in the links. Thank you.

Eliz.