Posted By admin on June 14, 2011

Coin Alexander

Probability can anyone help?

I cant figure out these four questions with probability, I suck with probability, could anyone help??

1.The probability that Bob and Sue Alexander will win the jitterbug contest is 0.7. Find the odds in favor of them winning.
2.A bag contains five red chips, three white chips, and two blue chips. Three chips are to be selected at random, without replacement. Find the probability that the all three will be white.
3.A coin is flipped and then a number from 1 through 4 is selected at random from a bag. Construct a tree diagram showing all the possible outcomes.
4.A litter of collie puppies consists of four males and five females. If one of the puppies is selected at random, find the probability that the puppy will be female.

I know there easy but I just cant grasp the concept.

1) It is 7:3

2) there are totally 10 chips; a chip is drawn one by one without replacement
The probability that they are all white is = (first white, second white, third white)
All these are independent, since first coming white in no way that affects drawing of second one as white or other color;

Hence the probability = (3/10)*(2/9)*(1/8) = 1/120
[There are only 3 white, hence first one is 3/10; then there will be 2 white with a total of 9, as no replacement is taking place; hence it is 2/9; similarly for the third one]

3) It is not possible for me to make the tree diagram here; but I can give it as ordered pairs, which you may convert to tree diagram.

First the coin is tossed, the outcome of which may be Head(H) or Tail(T)
Second any one of the numbers from (1, 2, 3, 4)

Possible outcomes are: {(H, 1), (H, 2), (H, 3), (H, 4), (T, 1), (T, 2), (T, 3), (T, 4)}

4) There are totally nine puppies, of which five are females; The event is one selected at random, which is female

Hence the probability of female = C(5,1)/C(9,1) = 5/9

Wish you are explained; have a nice time.

Category: Antiques
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