# math

posted by .

jerome morgan and bly compete in a 10 kilometer race with 5 other athletes. what are the odds that they finish in the top 3 places? i got 3 to 5 but my teacher marked it wrong and wanted us to find out why it was wrong on our own. help would be nice!

• math -

Make a table
--B1 B2 B3 B4 B5 B6 B7
J1 --y- y- n- n- n- n-
J2 y -- y- n- n- n- n-
J3 y y- -- n- n- n- n-
J4 n n- n- -- n- n- n-
J5 n n- n- n- -- n- n-
J6 n n- n- n- n- -- n-
J7 n n- n- n- n- n- --
The diagonal elemnts are not part of our possibilities because they can no both finish in the same position.
That leaves us with 42 possible outcomes
of those 42, six are y which means six of the 42 outcomes have both B and J in the first 3 places.
6/42 =3/21

• Trying to clean up table -

Make a table
--b1 b2 b3 b4 b5 b6 b7
J1 --y- y- n- n- n- n-
J2 y -- y- n- n- n- n-
J3 y y- -- n- n- n- n-
J4 n n- n- -- n- n- n-
J5 n n- n- n- -- n- n-
J6 n n- n- n- n- -- n-
J7 n n- n- n- n- n- --
The diagonal elements are not part of our possibilities because they can no both finish in the same position.
That leaves us with 42 possible outcomes
of those 42, six are y which means six of the 42 outcomes have both B and J in the first 3 places.
6/42 =3/21

• Oh well -

I can not get columns to line up no matter what I do using -- or - for spacers
you have 7 rows and seven columns
the diagonals, marked with -- are out because J and B can not finish in the same place.
The y solutions are the good ones.
The n solutions are no good.

• math -

there are 3 people not only 2

• math -

you left out morgan

• math -

the number of ways for J, M and B and 5 others can be arranged is
3!5!.
The number of ways all 8 can be arranged is 8!
so the prob that they will be the first 3 finishers
= 3!5!/8! = 1/56
but you asked for the odds
odds of some event = prob the event will happen : prob the event will not happen
= (1/56):(55/56)
= 1 : 55

• math -

For Jerome the chances are 3/8 (if all of the runners had equal ability). For Morgan, after Jerome had gotten first (let's say he did) then his chances would be 2/7. And for Bly his chances are 1/6. Now you have got to multiply them all together.

(3/8) (2/6) (1/6) = 1/56

i feel like this is the easy way of doing it...

## Similar Questions

1. ### math number story

julie arrived 20 minutes before the race began she started right on time. it took her 24 minutes to finish the 6 kilometer race. she stayed 10 minutes after the race to cool off;then she left. if she arrived at the race at9:10am,what …
2. ### School Learning Curve

Can someone explain to me the features of the 'learning curve'. I only just found out that teachers grade people's work against other students in the class, and it's something to do with "scaling", especially in English. I'm just curious …
3. ### math

rich ran a 5 kilometer race how many meters is five kilometer
4. ### Math

A race track tote board has the odds for a horse listed as 5 to 3. Tote boards list the odds that a horse will lose the race. If this is the case, what is the probability of the horse winning the race?
5. ### math

julie arrived 20 minutes before the race began. she started right on time. it took her 24 minutes to finish the6-kilometer race. she stayed 10 minutes after the race to cool off; she left. if she arrived at the race at 9:10a.m., what …
6. ### pre algebra

Jerome, Morgan, and Bly compete in a 10-kilometer race with 5 other athletes. What are the odds that they finish in the top 3 places?
7. ### math (ms sue)

how would I factor x to the thrid + 3x squared - x -3 I got (x+3) (x squared -1) and my teacher marked me wrong.
8. ### Ball Charter Math

Julia arrived 20 minutes before the race began. She started right on time. it took her 24 minutes to finish the 6-Kilometer race. She stayed 10 minutes after the race to cool off; then she left. If she arrived at the race at 9:10 A.M., …
9. ### Physics

during a race,a dragster is 200 meters from the finish line when something goes wrong and its stops accelerating.it travels at a constant velocity of45 meters per second for 3seconds to try to finish the race.How far from the finish …
10. ### math

Teacher: 15 seconds after the buzzer, the teacher has 135 meters to finish. 32 seconds after he left the starting line, the teacher has run 50 meters left. Usian Bolt: 22 seconds after the buzzer, Usain has 189 meters to finish.36 …

More Similar Questions