## anonymous one year ago http://s296.photobucket.com/user/ontoonex99/media/Screen%20Shot%202015-06-02%20at%207.37.12%20PM_zpseia5o480.png.html I need help number 18 and 20 please check number 18 did P(A and B)=P(A) X P(B) P(A and B) / P(B)= P(A) = 0.15/0.6 = 1/4 ?

1. phi

I would say $P(B|A)= \frac{P(A \cap B)}{P(A)}$ so $P(A)= \frac{P(A \cap B)}{P(B|A)}$ with P(B|A)= 0.6 and P(A $$\cap$$ B) =0.15 from which you get P(A)= 0.25

2. anonymous

ok,Thanks, can you do number 20?

3. phi

For Q20 there are 20 marbles , 9 of them red. so 9/20 chance of choosing a red marble on the first pick. If you put the marble back in, then you will have 9/20 chance of picking red on the second pick, and 9/20 on the third. thus $\left(\frac{9}{20}\right)^3$

4. phi

If you do not replace the marble, then the chance of picking a red marble on the first pick is 9/20, on the second 8/19 and on the third 7/18 thus $\left( \frac{9}{20}\right)\left( \frac{8}{19}\right)\left( \frac{7}{18}\right)$

5. phi

for part A, each time you pick is an independent event (because we put the marble back in the bag). That means each pick should be 9/20 and for multiple independent events, you multiply the individual probability to find the probability of all the events occurring.

6. anonymous

thanks , can you have me some more ?

7. anonymous
8. phi

ok

9. anonymous

this one I no idea

10. phi

for event A, you count up the number of tiles that are consonants (the problem is y is sometimes a vowel e.g. fly, by, dry, or as a consonant e.g. you, yell, young, ...) not sure how to handle that.

11. phi

and of course for B, first count the number of tiles that are vowels.

12. anonymous

let me know if later you can solve , I need help if you can check my work it correct

13. anonymous

can you check my answer ?

14. phi

Let's assume y is only a consonant. then there are 42 vowels, 2 blanks, 56 consonants the chance of choosing a consonant on the first draw is 56/100 and the chance of choosing a vowel on the 2nd draw is 42/99

15. phi

and we multiply (56/100)*(42/99)

16. anonymous

http://s296.photobucket.com/user/ontoonex99/media/Screen%20Shot%202015-06-02%20at%205.56.17%20PM_zpstctblc9x.png.html $\frac{ 1 }{6 }$ $\frac{ 1 }{ 6 } . of .60 = 10 ?$

17. phi

yes, and the 4 spot came up 10 times

18. anonymous

ok, next http://i296.photobucket.com/albums/mm168/ontoonex99/Screen%20Shot%202015-06-02%20at%205.56.23%20PM_zpscjpwjnoy.png $\frac{ 1 }{ 5 }\times30?$

19. phi

yes, so the black marble.

20. anonymous

thanks,next http://i296.photobucket.com/albums/mm168/ontoonex99/Screen%20Shot%202015-06-02%20at%205.56.08%20PM_zpszlf9z9b0.png $\frac{ 179 }{ 2237 }=0.0800$ 0.0800 x 100= 8% ?

21. phi

I would leave the answer as 0.08

22. anonymous

thanks http://s296.photobucket.com/user/ontoonex99/media/Screen%20Shot%202015-06-02%20at%205.56.29%20PM_zpsfhmscrjx.png.html $\frac{ 526 }{ 2392 }?$

23. phi

yes

24. anonymous
25. phi

your picture of the weather does not match up with 9/12000

26. anonymous

let me check

27. phi

for the weather question I think they want you to order A , B, C , D from least to most likely

28. anonymous
29. phi

9/1200 (not 12000) and expected number of defects is 9/1200 * 15000

30. anonymous

$\frac{ 9 }{ 1200 }\times1500?$

31. phi

yes

32. anonymous

let go back to number 22 D<B<A<C ?

33. phi

chance of rain on Fri is 5%, so chance of no rain is 95% i.e. D has prob= 95%

34. phi

and they want the order smallest to biggest. D will be the biggest chance.

35. phi

what numbers do you get for A, B , C and D ? for A and C, read off the number from the chart for B and D, do 100 - what is on the chart.

36. phi

I get A 80, B 70, C 90, D 95

37. anonymous

thanks you . Take me so long ti fix out , http://s296.photobucket.com/user/ontoonex99/media/Screen%20Shot%202015-06-02%20at%207.35.09%20PM_zpse2zctvy9.png.html 3) Dependent 4) independent