# Talk

## to think this was an unfair way to select children

(102 Posts)
3boys40 Tue 04-Nov-14 13:07:54

Given a number between 2 and 12 starting at the front of class. Than rolling a dice to select said children. You would think a maths teacher should know that gives certain children an unfair advantange. My poor ds who sits at the the front had no chance with 2.

AllSorted Tue 04-Nov-14 13:09:54

2 dice or a 12 sided die?

rebelfor Tue 04-Nov-14 13:10:04

2 has the same chance as any other number, on the basis of probabilities.

The odds are the same as any other numbers coming up. Maybe that's the point the maths teacher was making.

FrauHelga Tue 04-Nov-14 13:11:09

The odds are exactly the same on any number coming up - that's how probability works.

MustBeDueSomeBetterFeet Tue 04-Nov-14 13:11:42

I'm confused. Surely that's the whole point - that regardless of what number the kids were given, their CHANCE was exactly the same on the roll of a dice.

I'm not sure what the problem is?

Sprink Tue 04-Nov-14 13:12:42

Eh?

Psycobabble Tue 04-Nov-14 13:13:30

seems it's a good job its them that's the maths teacher !

LoblollyBoy Tue 04-Nov-14 13:13:49

It must have been two dice, surely, or OP wouldn't be so sad!

kelda Tue 04-Nov-14 13:13:57

I assume you mean two dice?

AllSorted Tue 04-Nov-14 13:14:10

I assume 2 dice were thrown and the numbers added. So for 2 you'd have to get 2 1s, but for 8 you could get 2,6 or 3,5 or 4,4 (plus opposite ways around) so better chance

LegoAcquaintance Tue 04-Nov-14 13:14:30

If it was 2 dice, then the odds are not the same, are they?

2 could only be 1 and 1.
Whereas 7 could be 1 and 6, or 2 and 5, or 4 and 3 - much more likely.

soupey1 Tue 04-Nov-14 13:14:30

Actually the probability is not the same for 2 or 12 since there is only one way to make it (assuming 2 x normal six sided dice). For the other numbers there are two possibilities and therefore twice the chance.

WishUponAStar88 Tue 04-Nov-14 13:14:34

I took it to mean 2 regular dice? So two 1s would need to be rolled to get to 2 but other numbers could be made from a variety of number combinations

Purplepixiedust Tue 04-Nov-14 13:14:40

??

Surely all have same chance?

WishUponAStar88 Tue 04-Nov-14 13:15:05

Haha lots of cross posting!

TheLyingOldBitchAndHerWardrobe Tue 04-Nov-14 13:15:15

The odds aren't the same though; if you were given a number six for example then if the dice rolls any of the combinations adding up to six the child is picked.

12 and 2 only have one combination possible.

Surely that means the odds are worse for those numbers?

I'm bit a maths bod though so may be completely misunderstanding.

soupey1 Tue 04-Nov-14 13:15:18

I should have said at least two ways as for some numbers there are even more.

MyGhostIsFlummoxed Tue 04-Nov-14 13:15:18

If it was 2 die then I guess there's more ways to get e.g 6 (5&1, 2&4, 3&3) then 2 (1&1), is that what you mean OP?

Purplepixiedust Tue 04-Nov-14 13:15:39

Buscake Tue 04-Nov-14 13:15:44

If it was 2 dice then 2 has only one chance ie if 2 1s are rolled. Compare this to 6 which could comprise of 3 + 3; 2 + 4; 1 + 5. Better to pull names out of a hat.

SaucyJackOLantern Tue 04-Nov-14 13:15:45

YANBU if it was two dice (die?)

There are six combo's that would give you a total of six (for example). Only two that give you a total of two.

cailindana Tue 04-Nov-14 13:16:03

The odds aren't the same. I presume the teacher was rolling two dice (hence being a number between two and 12). In that case, the only way to get a two is to roll a one and a one, whereas to get a 7, for example, you can roll a 3 and a 4, a 5 and a 2 or a 6 and a 1. The worst numbers to have in that scenario are 2, 3, 11 and 12 as there is only one way to obtain each of those numbers using two dice.

Thesimplethings Tue 04-Nov-14 13:16:09

Actually I see OP's point.

2 can only be made by the dice both falling on the number one.

6 for example can be made by the dice falling on 3/3, 4/2, 5/1 so more li

whatsonyourplate Tue 04-Nov-14 13:16:20

Assuming it was 2 dice, op is right. You can only get 2 by rolling 1, 1 but you could get say 5 by rolling 1,4; 2,3; 3,2; 4,1.

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