Answer: 0.9961
Step-by-step explanation:
Given: Total choices to each question = 4
So, the probability that an answer is correct = [tex]\dfrac{1}{4}=0.25[/tex]
Total questions = 20
i.e. n= 20
Let x be the binomial variable that represents the number of correct answers.
So, the probability that the student has at least 10 correct answers.
[tex]B(x=10;n=20, p=0.25)=\sum\limits_{i=0}^{x}(i;n=20,p=0.25)[/tex]
[tex]=0.9961[/tex] [By using cumulative binomial table]
Hence, the probability that the student has at least 10 correct answers = 0.9961
