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# Stats h/w need help😣 watch

1. 4 options 30 questions. he wants the probability of someone passing the test by guessing the answer to each question to be 10% or less. what is the lowest score that should be set as the pass mark?

If anyone could help it would be great
2. (Original post by Morgan111)
4 options 30 questions. he wants the probability of someone passing the test by guessing the answer to each question to be 10% or less. what is the lowest score that should be set as the pass mark?

If anyone could help it would be great
3. I know X~B(30,0.25) letting X be the probability that a student gets a question right by guessing.

And that it’s asking for P(X<x) <0.1 but I don’t know where to go from there.
4. (Original post by Morgan111)
I know X~B(30,0.25) letting X be the probability that a student gets a question right by guessing.

And that it’s asking for P(X<x) <0.1 but I don’t know where to go from there.
Are you doing old spec or new spec A Level?

You could either use a calculator to try different values of x until you get < 0.1. Or you could use probability tables which may be quicker if you've used them before?
5. Ok thank you ☺️ can’t believe I didn’t think of that !
(And old spec)

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