Question

laila guesses on all 20 questions of a multiple - choice test. each question has 4 answer choices. what is the probability of a success and a failure for this experiment?
p(success) = 1/4; p(failure) = 3/4
p(success) = 1/4; p(failure) = 1/2
p(success) = 3/4; p(failure) = 1/4
p(success) = 1; p(failure) = 0

Explanation:

Step1: Define success and failure probabilities

Success is getting a question right. Since there are 4 answer - choices for each question, the probability of getting a question right by guessing is $P(\text{success})=\frac{1}{4}$.
Failure is getting a question wrong. The probability of getting a question wrong is $P(\text{failure}) = 1 - P(\text{success})$.

Step2: Calculate the probability of failure

$P(\text{failure})=1-\frac{1}{4}=\frac{3}{4}$

Answer:

A. $P(\text{success})=\frac{1}{4};P(\text{failure})=\frac{3}{4}$