Question

Ten students are applying for 3 positions on a team. the students include 4 boys (adam, alex, anthony, and arnold) and 6 girls (abbey, aurora, agnes, alice, amanda, and anna). all the students have an equal chance of being selected. find the probability that the students selected will include: a) adam, anthony, and alice b) agnes and 2 other students

Answer 1

ok

Answer 2

adam anthony and alice, thats 3 people
so favorable is 3. and total is 10 choose 3 , correct ?

Answer 3

so 3 / 10 choose 3

Answer 4

3 / ( 10 choose 3) , remember 10 choose 3 is total ways of choosing 3 people out of ten , order does not count

Answer 5

that's it?

Answer 6

and 3 cuz you have 3 favorable, they specified

Answer 7

yeah, its easy :0

Answer 8

well that one anyway

Answer 9

brb

Answer 10

wait so answer is????

Answer 11

.025

Answer 12

fraction form?

Answer 13

3 / ( 120

Answer 14

1/40

Answer 15

wait, why does it matter?

Answer 16

probability is usually in fraction form

Answer 17

if youre doing this online, let me know if its correct

Answer 18

it can be a decimal between 0 and 1

Answer 19

ok

Answer 20

B now

Answer 21

wait, is it right ?

Answer 22

I'm not sure? going over it on monday

Answer 23

in class

Answer 24

let's do B

Answer 25

Lol

Answer 26

ok agnes, thats 1

Answer 27

2 other students? well there are 9 students left, and you choose 2

Answer 28

so 1 + 9 choose 2 , thats the favorable , and the denominator is again , the same

Answer 29

newton, do you concur?

Answer 30

( 1 + 9 C 2 ) / ( 10 C 3 )

Answer 31

oh newton is gone, darn

Answer 32

why did u add 1??

Answer 33

Oh by the way, if the answer to the first one is 1/40, and there are 10 * 9 * 8 ways of choosing the first 3 people, that implies that 18 teams will have those three in any order (they don't)

Answer 34

1 for agnes, since they told you , you must choose her

Answer 35

It makes more sense just to say there are 10C3 ways of picking the 3 students (nCr takes into account the ordering problem) and one of these will be the 3 we want - so it is simply 1/10C3, not 3/10C3

Answer 36

what??? I'm confused. what's the setup

Answer 37

i get 37/120 , unless i did something wrong

Answer 38

or should it be multiplied, hmmm

Answer 39

ohhh

Answer 40

sorry it is ( 1 * 9 choose 2 ) / 10 choose 3

Answer 41

since there is 1 way to choose agnes, then there is 2 you have to choose among the 9 left

Answer 42

so 36/ 120 = 3/ 10

Answer 43

ah I see lol, but I still don't understand this permutation and combination stuff? is there a way that u can explain to me?

Answer 44

permutations is where order counts, combination is where order does not count

Answer 45

thats the "big" difference

Answer 46

how do u know what numbers to put for the probability

Answer 47

like 9C2/10C3

Answer 48

I don't get how u set up the numbers in order to find the probability

Answer 49

well we use multiplication rule

Answer 50

there are how many ways to choose agnes, one way.
and for each of that way we can choose from whats left (9 people) 2 people we can choose. so we multiply these .

Answer 51

if you can do step one in k ways, and for each of those ways you can do step m, then there are a total of k * m ways

Answer 52

so we did ( 1 * 9C2) , thats the favorable

Answer 53

what grade r u in btw