Answer:
25
Step-by-step explanation:
he got an 80 so if that was his grade by answering 20 questions right then the correct answer would be 25 questions
Read the explanation
look at the photo
B
b
Total marble = 8+5+4 = 19
n(Y) = 8, n(B) = 4 and n(R) = 5
Prob(R) = 5/17
Prob(B) = 4/16 {one marble is pulled out already}
Prob(R and B) = 5/17 × 4/16
= 5/17 × 1/4
= 5/68
6
