### CFA Practice Question

There are 434 practice questions for this study session.

### CFA Practice Question

There are five multiple-choice questions on an exam, each with responses a, b, c, or d. Each question is worth 5 points and only one option per question is correct. Suppose a student guesses the answer to each question. His or her guesses from question to question are independent. If the student needs at least 20 points to pass the test, the probability that the student passes is closest to ______.

A. 0.0146
B. 0.0010
C. 0.0156

X, the number correct if you were guessing, is binomial with parameters n = 5 and p = 0.25. To get at least 20 points, the student must get at least 4 of the 5 questions correct. Choice A is the probability of getting exactly 4 correct and choice B is the probability of getting exactly 5 correct. The correct answer is P(X >= 4) = P(X = 4) + P(X = 5).

User Comment
moma20 p=0.25 because there is only 1 correct choice from the 4 choices
manessa can some explain how to arrive at the answer plz
RichWang P(4) = 5C4 * ( 0.25 ^ 4 ) * (0.75 ^1) = 0.0146
P(5) = 5C5 * ( 0.25 ^ 5 ) * (0.75 ^0) = 0.0010
P(4)+P(5)=0.0156
Rivermax good question
CFAonTheBrain this is going to be on the test im sure
hillrat what is 5C4 on the calculator, in fact what the heck is it?
anneki its for combination: 5 2nd + 4
cslau83 If we are only concern about passing, then shouldn't a direct calculation on x=4 be sufficient? Why do you need to add on the probability of getting all 5 correct??
dhess0 Anyone know how to do combination on hp12c?
jorgeman81 in the BAII I input 5 2nd + 4 and I get 5, any idea what I'm doing wrong?
jayj001 5 2nd nCr 4 =
mjwoulf jorgeman81, 5ncr4 does equal 5
in english this means there are 5 ways to get 4 our of 5, i.e.
1234
1235
1245
1345
2345
mjwoulf jorgeman81, 5ncr4 does equal 5
in english this means there are 5 ways to get 4 our of 5, i.e.
1234
1235
1245
1345
2345
Kaloyan Instructions on how to calc. nCx problems with HP12c are given on the bottom on the page h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?cc=us&taskId=120&prodSeriesId=33525&prodTypeId=215348&objectID=c01910446
Kaloyan better try with google, typing in and looking for "HP 12c Financial Calculator - Statistics - Rearranging Items"
kondagadu don't understand why it has to be X>=4 , why not just x=4 ?
johntan1979 To all those questioning x>=4... READ the last part of the question... "the probability that the student PASSES"

If it were asking for the probability that the student AT LEAST passes, then it should be only x=4
davcer student passes, so is the probability of getting 20 0r 25 points in the exam
alexmon83 hits too close to home, ahem.