Question

Help...
Elizabeth has two identical number cubes. Both cubes have faces numbered 1 thourgh 6. if Elizabeth rolls each cube once, what is the probability that the sum of the two numbers on the top faces will be 10.
Choices are
1/36
1/12
1/10
1/9

Answer 1

@ospreytriple

Answer 2

Hope you don't mind

Answer 3

Not at all. How many different combinations are there that add up to 10?

Answer 4

5+5=10
9+1=10
8+2=10
7+3=10
6+4=10

Answer 5

Is that right?

Answer 6

But each cube is numbered 1 through 6, so you can't use any numbers greater than 6

Answer 7

Oh yeah

Answer 8

5+5=10
6+4=10

Answer 9

Umm.. Is there more? I'm not sure...

Answer 10

Right. But here's a tricky bit about probability and counting. You also have to consider the order that the numbers come up. So the first cube could say 4 and the second cube could say 6. BUT the first cube could say 6 and the second cube could say 4. They gave to be counted as two different outcomes.

Answer 11

So how about
5+5
6+4
4+6
Understand?

Answer 12

Yes

Answer 13

Ok. Now how many possible outcomes are there. Remember that each cube has six possible outcomes. How many possible outcomes are there. Remember the fundamental counting principle

Answer 14

2?

Answer 15

I'm not sure...

Answer 16

Ahh.. Wait so 1

Answer 17

Because 4+6 and 6+4 are still the same right

Answer 18

Here's a hint:
1 & 1
1 & 2
1 & 3
up to
6 & 4
6 & 5
6 & 6

Answer 19

I still don't get it

Answer 20

OK remember earlier that, when you had two events, you multiplied the possibilities together?

Answer 21

Yeah

Answer 22

Well, there are six possibilities on the first cube and six possibilities on the second cube. How many possibilities in total?

Answer 23

36

Answer 24

so is it 1/36?

Answer 25

Correct. And three of those possibilities give a sum of 10. What's the probability?

Answer 26

5+5?

Answer 27

There are 3 successful outcomes out of a total of 36 outcomes. What's the probability?

Answer 28

@Madi_Lee

Answer 29

3/36 x/36?

Answer 30

Just 3/36. Now you have to reduce it to lowest terms

Answer 31

which is 1/36

Answer 32

Nope. Divide both numerator and denominator by 3 and what do you get?

Answer 33

\[\frac{ 3 }{ 36 } = \frac{ 3\times1 }{ 3\times12 }=?\]

Answer 34

Huh?

Answer 35

Oh nevermind 1 minute

Answer 36

1/12

Answer 37

Exactly. Well done.