QR Problems

[Rock23]

---

Members don't see this ad.

can anyone please show me how to solve these, thanks!

1. Probability of getting six tails out of 9 tosses of a coin?


2. If 3 cards are selected from a deck, find prob that all are black?

3. Purchased 3 yellow roses, 2 pink, 5 red, how many 3 rose arrangements are there?

4. Sin (3x-26) = 1/ csc(5x-60); find x

 

[fancymylotus]

can anyone please show me how to solve these, thanks!

1. Probability of getting six tails out of 9 tosses of a coin?


2. If 3 cards are selected from a deck, find prob that all are black?

3. Purchased 3 yellow roses, 2 pink, 5 red, how many 3 rose arrangements are there?

4. Sin (3x-26) = 1/ csc(5x-60); find x

the last one you set 3x-26=5x-60 since csc=1/sin🙂

 

[Notoriousjae]

3. 10 total arrangements i.e 2+5+3=10
and you need find how many 3 rose arrangements so
10!/3!=10*9*8/3*2*1=120

 

[GRAD]

does anyone have the rest of the answers- i hate prob too

 

[lifeisgood]

Black cards

(26/52)*(25/51)*(24/50)=2/17 ~ 0.12

 

[lifeisgood]

Topscore Test 1 QR. I missed it. I won't anymore though. 🙂


There's a formula:
Probability of r successes out of n attempts: (nCr) * (p^r) * (q^n-r)

p = probability of successes in a single trial
q = prob. of failure

nCr = (9x8x7x6x5x4)/(6x5x4x3x2x1) = 84

success = (1/2)^6 = 1/64
failures = (1/2)^3 = 1/8


Plug in all values into formula up top.

(84)(1/64)(1/8) = 21/128.

That's the way they explain it. There must be an easier way though?

I remembered this post.