Becky is tossing two six-sided number cubes. Find probability that the sum of the roll is 8, 9, or 10

Question

Please answer ASAP! Dont have to show work, just answer and brief explanation. Its a mulitple choice so I know it shoukd be one of these~ 1/36, 1/3, 1/6, or 1/2. HELP!

Answer 1

If you make a 6 by 6 arrangement and in each of the 36 boxes place the sum of the numbers 1-6 at the headings of the columns and rows, you will see that the sum 2 can occur in only one way (1,1), 3 can occur in two ways, etc.

 

Fill our this whole array and count (along a "diagonal" the total number of ways that totals of 8, 9 and 10 can occur.

Then P(sum of two dice is 8, 9 or 10) = (5+4+3) / 36 and you can reduce this.

 

This 'table' will enable you to answer many similar questions.