Question

To pass a true or false test a student must answer 8 out of 10 correct. What is the probability a student will pass if he quesses on all 10 questions?
Find the mean and standard deviation of correct answers.

Is it unusual for a student to pass by guessing?

Answer 1

need help ?

Answer 2

OMG U WATCH NARUTO

Answer 3

haha yea to both

Answer 4

we want
P( x > = 8) = P( x = 8 ) + P(x = 9) + P(x=10)

Answer 5

i already got the first question but dont know the other two ):

Answer 6

= 10 choose 8 * .5^10 + 10 choose 9 * .5^10 + 10 choose 10 * .5^10

Answer 7

for a binomial distribution mean = n*p , so 10*.5 = 5

Answer 8

and st. dev is sqrt( n * p * (1-p)) = sqrt( 10 * .5 * .5 )

Answer 9

so the mean is 5 answers, the st.dev is 1.5811

Answer 10

the probability of passing the test due to guessing is .05468 . I would say it is pretty unlikely

Answer 11

in other word, u didnt choose the thug lyfe, thug lyfe chose u.

Answer 12

why is it unusual?

Answer 13

because the probability of passing (getting 8 or more right) purely by guessing is so low

Answer 14

it says to explain why..

Answer 15

i got a high probability.... i think i made a mistake..

Answer 16

i understand! ty!

Answer 17

go back and do part a) again

Answer 18

P( x > = 8)
= P( x = 8 ) + P(x = 9) + P(x=10)
= 10 choose 8 * .5^10 + 10 choose 9 * .5^10 + 10 choose 10 * .5^10

Answer 19

i understand lol i did x< =8 instead of x>=8 xD