F5 math probablitity

可否列式 + 解釋

2. Peter and John take turns to throw a fair dice. The one who can get a '6' first
will win the game. If the game starts woth Peter, find the probabilities that
(a) Peter wins in the second round, (Ans:25/216)
(b) there is a winner in the second round. (Ans:275/1296)

3. The Police Department has just purchaed a new a lie detector. The officer
performed a test run by asking volunteers some questions. The results are
recorded in the following table.

Detector indicates truth:
Volunteer tells the truth (85)
Volunteer lies(7)

Detector indicates lie:
Volunteer tells the truth (15)
Volunteer lies(93)


Estimate the following based on th eabove data.

If the probabilty that Ernest lies is 1/10, what is the probabilty that the detector
indicates correctly? (Ans:429/500)