# Stats revision past paper - Got stuck with 3 simple question!

• Feb 25th 2011, 02:51 PM
tombuckers
Stats revision past paper - Got stuck with 3 simple question!
Okay so I am revising and don't get the following questions, could you also explain how to do it. The past paper is june 2010 if anyone is interested.

1.) Alan and Bill are trying to hit bulls eye on dart board (the game). The probability that Alan hits is: 0.2 and the probability that Bill hits it is: 0.3.
Find the probability that:

a.) Bill Wins the game with his first throw
b.) Bill wins the game with his second throw
c.) Bill wins the game.

2.) Jack is taking part in a quiz programme. For each question in the quiz, four alternative answers are given, only one of which is correct. Jack has probabliiliyyu of knowing the correct answer to a question, and when he does not know the correct answer, he chooses one of the 4 answers at random.

a.) Calculate the probability that Jack gives the correct answer to a question. (3)
b.) Given that Jack gave the correct answer to a question, find the probability that he knew the correct answer.

7.) Sheila buys two biased dice in a shop. Each time either of the dice is thrown, the probability of obtaining a six is 0.2.

a.) She throws one of the dice 50 times. Determine the probability that she obtains:
i.) Exactly 12 sixes
ii.) At least 10 sixes
• Feb 25th 2011, 02:53 PM
Plato
Hello and welcome to MathHelpForum.
You should understand that this is not a homework service nor is it a tutorial service. Please either post some of your own work on these problems or explain what you do not understand about the questions.
• Feb 25th 2011, 02:57 PM
tombuckers
Okay. For question 1:

I got:
a.) 0.3
b.) 0.45
c.) 0.6

Is that correct?
• Feb 25th 2011, 03:08 PM
Plato
Quote:

Originally Posted by tombuckers
1.) Alan and Bill are trying to hit bulls eye on dart board (the game). The probability that Alan hits is: 0.2 and the probability that Bill hits it is: 0.3.
Find the probability that:
a.) Bill Wins the game with his first throw
b.) Bill wins the game with his second throw
c.) Bill wins the game.

This question is too vague to answer.
Who throws first?
If Bill does then the answer to part (a) is \$\displaystyle 0.3\$.
However, if Alan goes first them Bill the answer is \$\displaystyle (0.8)(0.3)\$