Probability Questions?

Question

you flip a coin four times

you choose two different numbers from 1 to 5. This time (1,2) is different from (2,1)

Choose three letters from A,B,C, and D. This time (A,B,C) is the same as (A,C,B).

Flip a coin twice. You get two tails.

Flip a coin three times. You get two heads and one tail, not necessarily in that order.

Flip a coin four times. You get at least two heads in a row.

Find the theorectical probabilty of each of the following.

You buy 10 tickets for a drawing for a quilt in a volunteer fire department funde raiser. the derpartment sells 750 tickets. What is the probability that you will receive the quilt?

the average of Earth is approx. 3960 mi. Suppose that debris from a satellite lands randomly on the Earth's surface. What is the proability that it lands in the U.S. (area 3,615,100 mi squared)?

You flip a coin three coin at the same time.
a. list the sample space
b. What is the probablity of getting three heads?

b. What is t the probability of getting one head?

Answer 1

Some of the questions are unclear, but I'll do my best.

1) Flip a coin four times.

It doesn't matter how many times you flip it, the chance of heads or tails is always 1/2, or .5 or 50%

2) Choose two different numbers where 1,2 is different than 2,1

You have the following combinations:

1,2 2,1 3,1 4,1 5,1
1,3 2,3 3,2 4,2 5,2
1,4 2,4 3,4 4,3 5,3
1,5 2,5 3,5 4,5 5,4

So, the probability of picking any single combination is 1/16, or .0625, or 6.25 %

3) Choosing three letters, and reversed combinations are the same.

The combinations available are:

A,B,C
A,B,D
B,C,D
C,D,A

So, any single three letter combination is 1/4 or .25, or 25%

4) Flip a coin twice.

The chance of a tail (1/2) x the chance of a tail (1/2) = 1/4

5) Flip a coin three times, and get two heads (H) and one tail (T)

You can get:

HHH
HHT
HTT
HTH
THT
TTT
TTH
THH

So, there are eight combinations. Of those eight, there are only 3 that will give you two heads and a tail. Therefore, the probability is 3/8.

6) Flip the coin 4 times, and get two heads in a row.

HHXX
XXHH
XHHX

There are only 3 possible combinations of two heads in a row.

How many total combinations are there? The combination is either H or T and we are doing it four times! 2^4 = 16

So, the probability is 3/16.

7) You buy 10 tickets out of 750 = 10/750 = 1/75 or .013 or 1.3%

8) This question is unclear...I'm sorry. Just take the U.S. area and divide it into the average area of the earth.

9) Three coins at the same time:

You can get a heads or tails on each one, so the sample space is 2x2x2 or 8 possibilities.

The probability of three heads is 1/2 x 1/2 x 1/2 = 1/8...which makes sense. Of the eight possibilities, there is only *one* way to get three heads.

Hope it helped.

Regards,

Mysstere

Answer 2

You coud get the announcement "a purple ball has been drawn" within the following 2 methods: Case a million: A purple ball was once drawn (a million/6) and each A and B instructed the reality (two/three * four/five). All in combination that is eight/ninety Case two: A non-purple ball was once drawn (five/6) and each A and B instructed a lie (a million/three * a million/five). All in combination that is five/ninety So the risk you've got fallen into case a million is: eight/ninety / (eight/ninety + five/ninety) = eight/thirteen