Problem Solving Skills for Mathcounts Competitions

Mathcounts => Mathcounts => : ruiwca October 22, 2010, 06:00:12 AM

: help for a problem
: ruiwca October 22, 2010, 06:00:12 AM

Hi all:

My child has a mathcount problem which I am not sure where to start:
Three fair six-sided number cubes, each with faces labeled 0,2,4,6,8,10, are rolled. what is the probabilit that the sum of the numbers rolled is greater than 20? Express your nswer as a common fraction.

Thanks.

: Re: help for a problem
: 木牛流马 October 22, 2010, 03:24:41 PM

I got 35/216.

: Re: help for a problem
: Katalianna November 07, 2010, 11:23:38 AM

I calculated and had 11/36 as my answer.

: Re: help for a problem
: t130152 February 07, 2011, 01:55:55 PM

The same thing as a+b+c>10 where 0<=a,b,c<=5 or x+y+z<=4 where 0<=x,y,z<=4.  It has the same counts as x+y+z+w=4 where 0<=x,y,z,w<=4, that is 7 chooses 3 = 35.

: Re: help for a problem
: wxc0212 February 13, 2011, 10:50:33 PM

Could somebody please explain in detail how they solved this question. How did you get 35/216 or 11/36