Help solve simple math problem.

[Devante]

Hey guys.

Sounds dumb but how do I find the probability of the following question?

A class has 32 students. Out of that class, 4 will fail.
Rudy is in this class.
What is the probability of Rudy failing?

I keep coming up with 1/8 but I think I'm missing a step.

 

[Recorderdude]

4/32

divide both by four

1/8

it's that simple. 1/8 will fail and he has a 1/8 chance of failing. this could also be expressed as .125, 12.5% or 1:8.

 

[s4mid4re]

4/32

divide both by four

1/8

it's that simple. 1/8 will fail and he has a 1/8 chance of failing. this could also be expressed as .125, 12.5% or 1:8.

to be a little clearer, 1/8 = 1÷8
if you solve 1÷8, it becomes .125 (you can also solve by 4÷32 and get the same answer)
move the decimal 2 places to the right and you get the percentage (12.5%)
1:8 (one to eight) is the simplified ratio form. just think of the colon as a division sign.

 

[Nathan Drake]

I wanna say 1/256. There is a 4/32 chance that four of the students will fail. There is also a 1/32 chance that the student could be Rudy.

To account for this, you have to set it up as follows:
(4/32)(1/32) = 1/256 chance that the failed student is Ricky

I wanna go ahead and say this is wrong though. I could say how to do this perfectly if I felt like pulling out my notes from my mini-probability unit in Pre-Calculus earlier this year. Instead of people, it was dice. It was something like the odds of it being a number 1 - 3 in six rolls, and how many times the number 2 would show up and crap like that.

Take my answer with a grain of salt, or a shaker, or a factory full.

 

[s4mid4re]

I wanna say 1/256. There is a 4/32 chance that four of the students will fail. There is also a 1/32 chance that the student could be Rudy.

To account for this, you have to set it up as follows:
(4/32)(1/32) = 1/256 chance that the failed student is Ricky

I wanna go ahead and say this is wrong though. I could say how to do this perfectly if I felt like pulling out my notes from my mini-probability unit in Pre-Calculus earlier this year. Instead of people, it was dice. It was something like the odds of it being a number 1 - 3 in six rolls, and how many times the number 2 would show up and crap like that.

Take my answer with a grain of salt, or a shaker, or a factory full.

I don't think that's what's being asked. If my interpretation is correct, this would be a variant of the question:
One of the 4 students that are failing can be Rudy, out of a total of 32 students. What is the probability that Rudy is 1 of the 4 students?

 

[SinHarvest24]

you were just over-thinking things ^

The answer you got is correct. So is everyone else here.

 

[Devante]

Thanks guys. :>

 

[wasim]

looks like there are many maths genius here

( solution for my homeworks is here

)

 

[CarbonX13]

looks like there are many maths genius here

( solution for my homeworks is here

)

Um... this really takes nothing more than what you learn in maybe grade 4 elementary school...

 

[wasim]

looks like there are many maths genius here

( solution for my homeworks is here

)

Um... this really takes nothing more than what you learn in maybe grade 4 elementary school...

i learned this in 6th grade

 

[Chhotu uttam]

looks like there are many maths genius here

( solution for my homeworks is here

)

Um... this really takes nothing more than what you learn in maybe grade 4 elementary school...

i learned this in 6th grade

but i learned it in 9th grade.(joking)

 

[Nathan Drake]

I didn't start to learn how to add, subtract, multiply, and divide fractions until pre-algebra. Through elementary school, it was pretty much all basic shit and memorizing stuff you'll never need to memorize again.

 

[chris888222]

Darn my math sucks :/

 

[mcp2]

Here ya go

 

[SamAsh07]

^ You forgot to state - use magnets for faster calculation AND Math question writing teachers will go bankrupt.

 

[CarbonX13]

I didn't start to learn how to add, subtract, multiply, and divide fractions until pre-algebra. Through elementary school, it was pretty much all basic shit and memorizing stuff you'll never need to memorize again.

Maybe it's the States then. I learned how to divide, multiply, add, and subtract factions in grade 4, and BEDMAS and such by grade 5.

 

[Devante]

P.S. I was drunk when I made this thread. ;>