Answer:
0.2503
Step-by-step explanation:
To solve this , we use the Bernoulli trial equation.
Now, there are 10 questions with 4 options each. The total number of options is thus = 10 × 4 = 40 options
There are only 10 correct answers however. The probability of picking a correct answer is thus 1/4 or 0.25
Now we know there are 30 wrong options. The probability of picking a wrong option is 30/40 or 0.75
To answer 3 questions correctly, it means she would answer 7 wrongfully.
Now to complete the parameters for the bernoulli trial, we know she is making 3 correct choices. Now the number of ways to select three correct choices out of 10 is 10C3
Computing the Bernoulli trial, we have :
(10C3) × (0.25)^3 × (0.75)^10
= 0.2503
