Probability

[nidhi]

Q: your teacher knows 6 jokes and in each class tells two jokes ,each job has an equal chance being selected.what is the probability that, in a given lecture, at least 1 joke is told that was not told in previous class.?

[Swati jain]

its 6c2 -1 /6c2=28/30

[nidhi]

Please tell me how to go through this question


Q. Jai and Vijay are taking a exam in statistics. The exam has only three grades A,
B and C. The probability that Jai gets a B is 0.3, the probability that Vijay gets a B is
0.4, the probability that neither gets an A, but at least one gets a B is 0.1. What is the
probability that neither gets a C but at least one gets a B?
a) 0.1
b) 0.6
c) 0.8
d) Insufficient data to answer the question

[duck]

it is 0.6

just write the sample space and then work out .. :)