A student wants to buy 3 cds, but assume 5 cds feature the piano, 6 cds feature the trumpet, and 3 cds feature the saxaphone.
I figured there are 364 ways for 3 cd's to be selected.
In how many ways can the selection be made if cds featuring at least 2 different instruments are selected?_______________--

- anonymous

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- schrodinger

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- anonymous

Moving on to computing probabilities by using equally likely outcomes after this

- anonymous

haha

- anonymous

HOLY COW

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## More answers

- anonymous

How does that happen

- anonymous

i can copy and paste them

- anonymous

if you cant see the first part of your solution

- anonymous

no

- Directrix

I'll try again. Patience is a good thing. :)

- anonymous

you dont have to
I am considering moving on to some other stuff that i am not sure how to do at all

- anonymous

nope

- anonymous

i tried that earlier

- Directrix

I want to do it. You can move on to another problem while I work on this.

- anonymous

Your call man i have spent A LOT of time on these 27 questions
our exam questions are coming directly from these Homework problems like this

- anonymous

I will post another shortly im sure

- Directrix

Here's where I messed up. The problem is at least 2 different instruments are selected? I calculated at least 2 of the SAME instrument.

- anonymous

yes that is correct

- anonymous

i need to sign off for a moment bu i will be back in 5-10 mins at the most

- Directrix

Okay, no rush. I just cleaned up my work area for my next take on this problem.

- anonymous

im back around

- Directrix

P = Piano, S = Sax, T = Trumpet
Of the 3 cds we are buying, 2 could be of the same instrument and 1 of another instrument.
I see the following cases:
PPT, PTT and PPS, PSS, and TTS, TSS. Do you see others before we calculate?

- anonymous

I don't

- Directrix

PPT, PTT
PPT==> C(5,2) times C(6,1) = 60
PTT ==> C(5,1) times C(6,2) = 75
Subtotal 1: 135 (Not Finished)

- Directrix

PPS, PSS
PPS ==>C (5,2) times C (3,1) = 30
PSS ==> C(5,1) times C(3,2) = 15
Subtotal 2: 45 (Not Finished)

- Directrix

TTS, TSS
TTS==> C(6,2) times C(3,1) = 45
TSS ==> C(6,1) times C(3,2) = 18
Subtotal 3: 63 (Not Finished)

- Directrix

Answer: Total of Subtotals of cases: 135 + 45 + 63 = 243 ways.

- Directrix

CW, what about this answer of 243?

- anonymous

no it didnt work

- Directrix

What did we miss? By the way, is 314 the answer? I don't think so but tried something different.

- anonymous

no

- Directrix

We missed the case where all three are different such as P T S

- anonymous

hmmm

- Directrix

PTS
C(5,1) times C(6,1) times C(3,1) = 90

- Directrix

So, the corrected answer is the
Answer: Total of Subtotals (exactly 2 different cases plus all 3 differnt: : 135 + 45 + 63 + 90 =333. Answer:333

- Directrix

Bad news, CW?

- anonymous

what?

- Directrix

The answer -- 333. Right or wrong.

- anonymous

right hahaha

- anonymous

awesome man

- anonymous

ly cow

- anonymous

holy

- Directrix

Sure it's right? There may be another case out there, and we'll find it.

- anonymous

no that is correct

- Directrix

Okay, where are the other problems?
"I will post another shortly im sure" you said.

- anonymous

yea i will in a moment

- anonymous

they are a different section

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