ramone has 5 difficult questions left to answer on a multiple choice test. Each question has 3 choices. For the first 2 of these
questions, he eliminated 1 of the 3 choices. find the probability that he will answer the first 2 questions, as well as at least 2 of the 3 remaining questions correctly.
then she eliminated 1 choice in 1 and 2, say as follows
1. b c 2. a b 3. a b c 4. a b c 5. a b c
Probability of answering correctly the first 2, and at least 2 or the remaining 3 is P(answering 1,2 and exactly 2 of 3.4.or 5.)+P(answering 1,2 and also 3,4,5 )
P(answering 1,2 and exactly 2 of 3.4.or 5.)= P(1,2,3,4 correct, 5 wrong)+P(1,2,3,5 correct, 4 wrong)+P(1,2,4,5 correct, 3 wrong) also P(1,2,3,4 c, 5w)=P(1,2,3,5 c 4w)=P(1,2,4,5 c 3w ) so P(answering 1,2 and exactly 2 of 3.4.or 5.)=3*P(1,2,3,4)=3*1/2*1/2*1/3*1/3*2/3=1/4*2/9=2/36=1/18
You have to find the scaling of the lengths first, and to do that, you divide the 20 by 8, which would be 2.5. After, you multiply 2.5 by 12 to get your answer.
