SOLUTION: Suppose that a quiz consists of 20 True-False questions. A student hasn't studied for the exam and will just randomly guesses at all answers (with True and False equally likely). H

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Question 1119938: Suppose that a quiz consists of 20 True-False questions. A student hasn't studied for the exam and will just randomly guesses at all answers (with True and False equally likely). How would you find the probability that the student will get 8 or few
Answer by M.Abdullah(2) (Show Source):
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By Using Binomial Distribution
Formula (nCx)
In this Problem Prob. of Success is 0.5 and Prob. of Failure is also 0.5
Remember that p+q=1
So Question is Find Prob. of Correct Question is 8 or Less than 8
Stepwise Solution
P(x=0)=20C0*0.5^0*0.5^20=1/1048576
P(x=1)=20C1*0.5^1*0.5^19=5/262144
P(x=2)=20C2*0.5^2*0.5^18=95/524288
P(x=3)=20C3*0.5^3*0.5^17=285/262144
P(x=4)=20C4*0.5^4*0.5^16=4.621*10^-3
P(x=5)=20C5*0.5^5*0.5^15=969/65536
P(x=6)=20C6*0.5^6*0.5^14=0.03696
P(x=7)=20C7*0.5^7*0.5^13=4845/65536
P(x=8)=20C8*0.5^8*0.5^12=0.1201
Sum up All the Answers>>>>>=0.2475