Answer:
0.051
Step-by-step explanation:
Each question has five choices.
So , probability of correct answer is 1/5 i.e.0.2
p = 5
Total number of questions = 5
n = 5
Let X be the number of questions that are correctly answered.
X follows Binomial(5 , 0.2)
Using binomial probability formula ,
P(X = x) = (ₙ C ₓ) * pˣ * (1 - p)ⁿ₋ˣ ; x = 0 ,1 , 2 , ....., n
Find P (Exactly 3)
= P(X = 3)
= (₅C ₃) * 0.2³ * (1 - 0.2)⁵ ⁻ ³
= (₅ C ₃) * 0.2³ * (1 - 0.2)²
= 0.051
