Page 87 - Peluang 2022 part Gabungan_Neat

Erin thinks of a number from 1 to 10 (say 8) and asks Peter

to guess what it is. Find the probability that Peter makes a

correct guess on his first try if Erin first tells Peter that the

number is greater than 7.

Answer Peter can choose one of

the three numbers available

10 8 n(B) = 3

9 Peter only had one correct guess

n(A  B) = 1

Let A is the event n(A  B) 1

that Peter guesses P(A|B) = =

correctly n(B) 3