i need help with a probability question

- anonymous

i need help with a probability question

- Stacey Warren - Expert brainly.com

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- anonymous

I can probably help you

- anonymous

can you post ?

- anonymous

oh your typing it. sry didnt see.

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## More answers

- anonymous

my question is a test consists of 20 tru/false question to pass a student must answer 18 corectly .. if a student guesses on each question, what is the probability that the student will pass the test ?

- anonymous

I think 40%

- anonymous

Very close to zero, give me a minute to get the exact answer

- anonymous

It is definitely not 40%. Much lower

- anonymous

can you tell me like how to get the answer

- anonymous

it would help me alot

- anonymous

probably. I totally forgot this subject.

- anonymous

So...try getting the probability of one correct answer. True or false. That is 50%

- anonymous

If you guess on a tru/false, thats 50 percent for each answer.

- anonymous

so you use that and 20 get your percentage
then subtract 2
I think...

- anonymous

Now try two answers correct. He has to guess 50% correctly twice. To answer two correct questions he has to get 50% twice

- anonymous

To answer 18 correct he's have to be some kind of superhero

- anonymous

so it will be like .50*.50 ?

- anonymous

Dude this is really hard to think right now i'm totally stoned out of my mind

- anonymous

.50*.50 18 times ?

- anonymous

maybe its like .50 times 18

- anonymous

maybe its like
.5^18

- anonymous

OH NO NOW I REMEMBER

- anonymous

what you have to do it find the probability of him NOT getting 18. And subtract that from 100%

- anonymous

So in order to not get 18 correct he has to get three incorrect am i right?

- anonymous

yea

- anonymous

how do you find the probability of getting three incorrect?

- anonymous

do you know any good way to get blood out of my keyboard? Its gotten to the point where its just nasty

- anonymous

? what does that have 2 wid anething ?

- anonymous

dude i don't know i'm just trying to help you maybe you could help me too

- anonymous

get alcohol pads probably

- anonymous

that actually sounds like a good idea actually has this worked for you in the past?

- anonymous

dude just like find the prob. of getting three wrong then subtract. its very easy

- anonymous

R u talkin bout my errors?

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