# probability

• Jun 21st 2008, 01:43 PM
probability
can anyone tell me wether these statements are Bionimial Distribution and why?

1) A school car park has 5 spaces. the number of spaces filled at the same time each day

2) A group of students is selected and they are asked to each take 8 shots at netball. For each student record the number of successful shots.

3) A fair coin is spun untill a head occurs. How many spins are required untill the head occurs?

4) A jar contains 49 balls numbered 1 to 49. six of the balls are selected at random. find the probability that four of the six have an even score
• Jun 21st 2008, 04:11 PM
mr fantastic
Quote:

can anyone tell me wether these statements are Bionimial Distribution and why?

1) A school car park has 5 spaces. the number of spaces filled at the same time each day

Mr F says: Does the value of p stay the same for each day ......? Monday versus Sunday?

2) A group of students is selected and they are asked to each take 8 shots at netball. For each student record the number of successful shots.

Mr F says: The question asker probably intends the answer to be yes. That's the answer I'd give. But .....

does a student become a better shooter with a little bit of practice? Will the value of p stay the same ......? I know my shooting would probably improve from shot 1 to shot 8. And is the shot taken from the same spot each time under identical conditions?

3) A fair coin is spun untill a head occurs. How many spins are required untill the head occurs?

Mr F says: No. There are not two possible outcomes - success or failure in each trial. Research Geometric Distribution.

4) A jar contains 49 balls numbered 1 to 49. six of the balls are selected at random. find the probability that four of the six have an even score.

Mr F says: No. See below.

For a random variable to follow a binomial distribution, there are three criteria that need to be met. Are you familiar with them?
• Jun 22nd 2008, 01:09 AM
Re: probability
Thanks very much for your help!

could you also help me with this? is this Binomial Distribution?

A card is selected at random from a standard pack of 52 playing cards. The suit is recorded and the card is replaced. This process is repeated to give a total of 16 selections, and on each occasion the card is replaced in th pack before another selection is made. Calculate the probability that exactly 5 hearts occur in the 16 selections.
• Jun 22nd 2008, 01:19 AM
mr fantastic
Quote:

Thanks very much for your help!

could you also help me with this? is this Binomial Distribution?

A card is selected at random from a standard pack of 52 playing cards. The suit is recorded and the card is replaced. This process is repeated to give a total of 16 selections, and on each occasion the card is replaced in th pack before another selection is made. Calculate the probability that exactly 5 hearts occur in the 16 selections.

Note: New and unrelated questions require new threads.

Let X be the random variable number of hearts.

Then X ~ Binomial(n = 16, p = 1/4).

Find Pr(X = 5).

Note: \$\displaystyle \Pr(X = r) = {n \choose r} p^r (1 - p)^{n-r}\$.

In your case, r = 5 .....
• Jun 22nd 2008, 04:33 AM