Q&A - PSLE Math

[Ender]

" Susan has two children. They are not both boys.What is the chance that both children are girls?"

Pls discuss which answer is correct.

Answer 1: 1/3 (answer given by setter)

Answer 2: 1/2

My take would be 1/3, because the condition of both boys is removed, so 1 less possible condition. Total possible combo would 3.
It's either
1. G and G
or
2. B and G
or
3. G and B

[Polar_bear]

" Susan has two children. They are not both boys.What is the chance that both children are girls?"

Pls discuss which answer is correct.

Answer 1: 1/3 (answer given by setter)

Answer 2: 1/2

My take would be 1/3, because the condition of both boys is removed, so 1 less possible condition. Total possible combo would 3.
It's either
1. G and G
or
2. B and G
or
3. G and B

So If the question changed to "Susan has two children. They are not both boys.What is the chance that she has one boy and one girl?", your answer is 1/3 or 1/2?

[Ender]

" Susan has two children. They are not both boys.What is the chance that both children are girls?"

Pls discuss which answer is correct.

Answer 1: 1/3 (answer given by setter)

Answer 2: 1/2

My take would be 1/3, because the condition of both boys is removed, so 1 less possible condition. Total possible combo would 3.
It's either
1. G and G
or
2. B and G
or
3. G and B

So If the question changed to "Susan has two children. They are not both boys.What is the chance that she has one boy and one girl?", your answer is 1/3 or 1/2?

2/3..
2 out of possible 3.

[Polar_bear]

Thanks Ender, even so i am still confused... for me, one boy and one girl no matter who born first, only one condition.

[Ender]

Thanks Ender, even so i am still confused... for me, one boy and one girl no matter who born first, only one condition.

Let's say we have 2D instead of 4D lottery.
1st digit can be from 0 to 9. 2nd digit can be from 0 to 9. Are total combinations 100 or 50, if you don't count reverse numbers?

My take is 100. because we have to counted in the reverse number. e.g. 12 is counted as one combo, and the reverse 21 is counted as another combo. The chance of striking a 55 is 1/100 and not 1/50.

So in a real 4D , the chance of striking a 5555 is 1/10,000 and not 1/5,000.

[Polar_bear]

Thanks Ender, even so i am still confused... for me, one boy and one girl no matter who born first, only one condition.

Let's say we have 2D instead of 4D lottery.
1st digit can be from 0 to 9. 2nd digit can be from 0 to 9. Are total combinations 100 or 50, if you don't count reverse numbers?

My take is 100. because we have to counted in the reverse number. e.g. 12 is counted as one combo, and the reverse 21 is counted as another combo. The chance of striking a 55 is 1/100 and not 1/50.

So in a real 4D , the chance of striking a 5555 is 1/10,000 and not 1/5,000.

OK, I finally understand. Really Thanks!

[Polar_bear]

Which one odd? Why?Thanks!

[Nebbermind]

" Susan has two children. They are not both boys.What is the chance that both children are girls?"

Pls discuss which answer is correct.

Answer 1: 1/3 (answer given by setter)

Answer 2: 1/2

I donch think this is PSLE qn, ya?

[sushi88]

Which one odd? Why?Thanks!

D is odd one out.

[sushi88]

" Susan has two children. They are not both boys.What is the chance that both children are girls?"

Pls discuss which answer is correct.

Answer 1: 1/3 (answer given by setter)

Answer 2: 1/2

I donch think this is PSLE qn, ya?

Yeah, this is probability, out of syllabus.