Assignment 10

course Mth 152

xY]⾳assignment #010

010. `Query 10

Liberal Arts Mathematics II

03-14-2008

......!!!!!!!!...................................

12:53:23

Query 12.5.6 fair dice game pays $3 for 6, $2 for 5, $1 for 4. What is a fair price to pay for playing this game?

......!!!!!!!!...................................

RESPONSE -->

3*6/6 + 2*5/6 + 1*4/6 = 18/6 + 10/6 + 4/6 = 32/6 = $5.33

.................................................

......!!!!!!!!...................................

12:56:19

** A 1 in 6 chance of getting $3 is worth 1/6 * $3 = $.50 .

A 1 in 6 chance of getting $2 is worth 1/6 * $2 = $.33 1/3 .

A 1 in 6 chance of getting $1 is worth 1/6 * $1 = $.16 2/3 .

The total expectation is $1.00 * 1/6 + $2.00 * 1/6 + $3.00 * 1/6 = $1.00

So a fair price to pay is $1.00 **

......!!!!!!!!...................................

RESPONSE -->

I used the number we wanted to roll as the numerator instead of doing 1 in 6 chances of getting the number.

.................................................

......!!!!!!!!...................................

13:01:45

Query 12.5.10 expectation Roulette $1 bet 18 red, 18 black one zero

What is the expected net value of a bet on red?

......!!!!!!!!...................................

RESPONSE -->

18 red, 18 black, 1 zero

($1) 18/27 + (-$1) 19/27 = 18/27 - 19/27 = -1/27

.................................................

......!!!!!!!!...................................

13:02:50

** If your net gain is $1 for a win and -$1 for a loss the expected value is

18/37 * (+1) + 19/37 * (-1) = -$.027. **

......!!!!!!!!...................................

RESPONSE -->

I did not put it in money form

.................................................

......!!!!!!!!...................................

13:36:17

Query 12.5.20 exp sum of 2 of 5 cards 1-5.

What is the expected sum of the numbers on the two cards drawn?

......!!!!!!!!...................................

RESPONSE -->

5/5 + 4/5 + 3/5 + 2/5 + 1/5 = 15/5 = 3

.................................................

......!!!!!!!!...................................

13:41:49

** You can't get a sum of 1 on two cards. There is also no way to get a sum of two, since the lowest total possible is 1 + 2 = 3.

There are 2 ways to get total 3. You can get 1 on the first and 2 on the second, or vice versa.

There are 2 ways to get total 4. You can get 1 on the first and 3 on the second, or vice versa.

There are 4 ways to get total 5. You can get 1 on the first and 4 on the second, or vice versa, or 2 on the first and 3 on the second, or vice versa.

There are 4 ways to get total 6. You can get 1 on the first and 5 on the second, or vice versa, or 2 on the first and 4 on the second, or vice versa.

There are 4 ways to get total 7. You can get 2 on the first and 5 on the second, or vice versa, or 4 on the first and 3 on the second, or vice versa.

There are 2 ways to get total 8. You can get 3 on the first and 5 on the second, or vice versa.

There are 2 ways to get total 9. You can get 4 on the first and 5 on the second, or vice versa.

You can't get more than 9.

There are 2+2+4+4+4+2+2 = 20 possibilities, so the probabilities are 2/20, 4/20, 5/20, etc..

The expected sum is therefore

2/20 * 3 + 2/20 * 4 + 4/20 * 5 + 4/20 * 6 + 4/20 * 7 + 2/20 * 8 + 2/20 * 9.

This gives 120 / 20 = 6. **

......!!!!!!!!...................................

RESPONSE -->

I didn't work it like this at all and didn't even come close to the right answer. I see how you got the answer you figure how many ways there are to get answers and then multiply the answer by the possibilities.

.................................................

......!!!!!!!!...................................

13:42:27

Query Add comments on any surprises or insights you experienced as a result of this assignment.

......!!!!!!!!...................................

RESPONSE -->

I wasn't sure of how to work the last problem but after seeing how you worked it, I know now.

.................................................

I think you're in good shape. Let me know if you have questions.

Assignment 10

course Mth 152

xY]⾳assignment #010

010. `Query 10

Liberal Arts Mathematics II

03-14-2008

......!!!!!!!!...................................

12:53:23

Query 12.5.6 fair dice game pays $3 for 6, $2 for 5, $1 for 4. What is a fair price to pay for playing this game?

......!!!!!!!!...................................

RESPONSE -->

3*6/6 + 2*5/6 + 1*4/6 = 18/6 + 10/6 + 4/6 = 32/6 = $5.33

.................................................

......!!!!!!!!...................................

12:56:19

** A 1 in 6 chance of getting $3 is worth 1/6 * $3 = $.50 .

A 1 in 6 chance of getting $2 is worth 1/6 * $2 = $.33 1/3 .

A 1 in 6 chance of getting $1 is worth 1/6 * $1 = $.16 2/3 .

The total expectation is $1.00 * 1/6 + $2.00 * 1/6 + $3.00 * 1/6 = $1.00

So a fair price to pay is $1.00 **

......!!!!!!!!...................................

RESPONSE -->

I used the number we wanted to roll as the numerator instead of doing 1 in 6 chances of getting the number.

.................................................

......!!!!!!!!...................................

13:01:45

Query 12.5.10 expectation Roulette $1 bet 18 red, 18 black one zero

What is the expected net value of a bet on red?

......!!!!!!!!...................................

RESPONSE -->

18 red, 18 black, 1 zero

($1) 18/27 + (-$1) 19/27 = 18/27 - 19/27 = -1/27

.................................................

......!!!!!!!!...................................

13:02:50

** If your net gain is $1 for a win and -$1 for a loss the expected value is

18/37 * (+1) + 19/37 * (-1) = -$.027. **

......!!!!!!!!...................................

RESPONSE -->

I did not put it in money form

.................................................

......!!!!!!!!...................................

13:36:17

Query 12.5.20 exp sum of 2 of 5 cards 1-5.

What is the expected sum of the numbers on the two cards drawn?

......!!!!!!!!...................................

RESPONSE -->

5/5 + 4/5 + 3/5 + 2/5 + 1/5 = 15/5 = 3

.................................................

......!!!!!!!!...................................

13:41:49

** You can't get a sum of 1 on two cards. There is also no way to get a sum of two, since the lowest total possible is 1 + 2 = 3.

There are 2 ways to get total 3. You can get 1 on the first and 2 on the second, or vice versa.

There are 2 ways to get total 4. You can get 1 on the first and 3 on the second, or vice versa.

There are 4 ways to get total 5. You can get 1 on the first and 4 on the second, or vice versa, or 2 on the first and 3 on the second, or vice versa.

There are 4 ways to get total 6. You can get 1 on the first and 5 on the second, or vice versa, or 2 on the first and 4 on the second, or vice versa.

There are 4 ways to get total 7. You can get 2 on the first and 5 on the second, or vice versa, or 4 on the first and 3 on the second, or vice versa.

There are 2 ways to get total 8. You can get 3 on the first and 5 on the second, or vice versa.

There are 2 ways to get total 9. You can get 4 on the first and 5 on the second, or vice versa.

You can't get more than 9.

There are 2+2+4+4+4+2+2 = 20 possibilities, so the probabilities are 2/20, 4/20, 5/20, etc..

The expected sum is therefore

2/20 * 3 + 2/20 * 4 + 4/20 * 5 + 4/20 * 6 + 4/20 * 7 + 2/20 * 8 + 2/20 * 9.

This gives 120 / 20 = 6. **

......!!!!!!!!...................................

RESPONSE -->

I didn't work it like this at all and didn't even come close to the right answer. I see how you got the answer you figure how many ways there are to get answers and then multiply the answer by the possibilities.

.................................................

......!!!!!!!!...................................

13:42:27

Query Add comments on any surprises or insights you experienced as a result of this assignment.

......!!!!!!!!...................................

RESPONSE -->

I wasn't sure of how to work the last problem but after seeing how you worked it, I know now.

.................................................

I think you're in good shape. Let me know if you have questions.