probability help!! (1 Viewer)

[survivor]

hey if anyone can help me out with these questions it would be great!! thankyou in advance if you can

1.) an integer n, where 1<= n <=299, is selected at random. what is the probability that it is
a. divisible by 5?
b. not a multiple of 5?


2.) A and B play a game of chance. A tosses two dice and wins if he scores a 5 or 7. B draws two discs, without replacement from a bag containing 5 discs numbered 1,2,3,4,5 and wins if the sum of the numbers drawn exceeds 6.
who has the greater chance of winning and by how much?


thankyou again...............

 

[wogboy]

1) Firstly, how many integers are there in total? 299. And how many integers divisible by 5? Well there's: 5,10,15,...,295 which total up to 295/5 = 59.

So the probability of the random integer being divsible by 5 is 59/299

The probability of the integer not being divisible by 5 is 1 - 59/299 = 240/299

2) The probability of A winning is:

There are 6*6=36 possible ways of rolling two dice. How can person A win? If he rolls: (1,4) (2,3) (3,2) (4,1) (1,6) (2,5) (3,4) (4,3) (5,2) (6,1) --> 10/36 chance of winning
= 5/18 chance of winning.

The probability of B winning is:

There are 5*4=20 ways to draw these discs. He will win if he draws: (2,5) (3,4) (3,5) (4,3) (4,5) (5,2) (5,3) (5,4) --> 8/20 chance of winning
= 2/5 chance of winning.

You can see who has the greater chance of winning.

 

[survivor]

thankyou
one more question
if u have for example...
results of an election were as follows- party x 60%
- party y 40%
and then 2 voters are selected at random(ie from either party x or y)
does the percentage change, like when you do a prob tree , for the second draw???

 

[-=«MÄLÅÇhïtÊ»=-]

? can u rephrase your question a little. like give it in the form of the actual question.

 

[NSBHSchoolie]

i wouldn't say so. you aren't given enough info to change the percentages.