Question

Alex surveyed his classmates to determine who has been surfing and who has been snowboarding. Let A be the event that a classmate HAS snowboarded and let B be the event that a classmate HAS surfed.

If Alex picked a classmate at random, what is P(B/A) ?

A. 4/21
B. 3/4
C. 4/25
D. 25/28

Answer 1

surburu

Explanation:

Answer 2

B.
`(3)/(4)`

Explanation:

I got this question correct. :)

• A: Snowboarded
• B: Surfed

P(B|A) = P(A and B) / P(A)

P(Surfed|Snowboarded) = P(Surfed and Snowboarded) / P(Snowboarded)

• Amount surfed and snowboarded: 36
• Total amount snowboarded: 48

P(B|A) =
`(36)/(48)` =
`(3)/(4)`

Apologies for lack of explanation, but I think this will do it.