Probability help needed. (1 Viewer)

[EViL.GENiUS]

Hi

iam stuck on this question.

In a certain strain of plant the probability that a seed will produce a pink flower is 0.2. Determine the least number of seeds that must be planted in order that the probability of obtaining at least one pink flower exceeds 0.99.

 

[wendus]

probability is my worst topic. i can't help you sorry ): i think you use inequalities somewhere in there but you probably already know that lol.

 

[lolokay]

probability of getting all pink ones must be less than 1-0.99 = 0.01
(4/5)^n < 0.01
log_0.80.01 = 20.63
therefore n = 21

 

[EViL.GENiUS]

thanks lolokay for that really quick reply.

 

[EViL.GENiUS]

Hi

Could someone help me also on this question.

Thanks

 

[lolokay]

i) 6 ways to arrange the other 3, 4 ways to include kylie and jason, 2 ways to order those 2
6*4*2 = 48 ways
5! ways altogether = 120
2/5 probability

ii) what exactly does alternate mean?

iii) 8!/(4!4!) * 6!/5!
4/8*5/6 = 5/12

 

[EViL.GENiUS]

Hi

Also if you could sole these questions it would be really great.

Thanks

 

[wixxy2348]

Hi

Also if you could sole these questions it would be really great.

Thanks

I don't have a calculator
But are they seriously extension questions??

 

[wixxy2348]

found calculator.

answer to q5...
a) 0.0333 (use a probability tree)
b) 4/10 x 3 = 1 card of the three

 

[wixxy2348]

7. a) 0.0173

 

[wixxy2348]

And i THINK...
not 100% coz im really tired..
7. b) 0.1989
c) ARGH MY CALCULATOR DIED...
umm the working for (c) is...

((2/3)^8)+((1/3)^2)+((2/3)^9)+(1/3)+((2/3)^10)
should equal about 0.5

 

[volcanojet]

is the answer for question 4

P(defective) = 0.05740

 

[wixxy2348]

and thats all i can think of off the top of my head
i know how to do the others but yeah not off my head haha
p.s. GENERAL MATHS POWER!

 

[lolokay]

Hi

Also if you could sole these questions it would be really great.

Thanks

4. total of 10 bolts
P = (1/10)³(9/10)⁷*10!/7!3!

5. 4/10 * 3/9 * 2/8 = 1/30

b) combiantions:
4 combinations of 3 red
6*6 = 36 combinations of 2 red, 1 black
4*15 = 60 combinations of 1 red, 2 black
6*5*4/6 = 20 combinations of 3 black

so greatest probability of 1 red

6. P4 = 1/4 = 3/12, P2 = 5/12
this leaves 4/12 distributed among 4 scores = 1/12 for each of 1,3,5,6
to obtain a score of 5 you must role 1 and 4 or 2 and 3 (in any order
P(1,4) = 1/4 * 1/12 * 2 = 1/24 = 3/72
p(2,3) = 5/12 * 1/12 * 2 = 5/72
P(5) = (3+5)/72 = 1/9

7. a) (2/3)¹⁰

b) (1/3)^6/*(2/3)⁴ * 10!/6!4!

c) P(10) = (2/3)¹⁰
P(9) = (2/3)⁹*(1/3)*10
P(8) = (2/3)⁸*(1/3)²*10!/8!2!

then add probabilities

 

[volcanojet]

i) 6 ways to arrange the other 3, 4 ways to include kylie and jason, 2 ways to order those 2
6*4*2 = 48 ways
5! ways altogether = 120
2/5 probability

i think its should only be (4*2)/5! = 1/15


could someone check and see if iam right or wrong

i think it only matters where kyile and jason sit not where the other sit.

 

[erm]

i don't know why, but 2U probablity shits me. on the other hand i love permutations and combinations.

weird.