A box contains four blue and eight red balls. Jim and Jack start drawing balls from the box, respectively, one at a time, at random, and without replacement until a blue ball is drawn. What is the probability that Jack draws the blue ball?

the probability that Jack draws the blue ball is 0.38539

Step-by-step explanation:

Given the data in the question;

box contains

blue balls = 5

red balls = 8

Jim and Jack start drawing balls from the box, respectively, one at a time, at random, and without replacement

Now,

on the first attempted;

⇒ ( 8/13) × ( 5/12) = 10/39  

on the second attempt;

⇒ ( 8/13 ) ( 7/12) ( 6/11 ) ( 5/10 ) = 14/143

on the third attempt;

⇒ ( 8/13 ) ( 7/12) ( 6/11 ) ( 5/10 ) ( 4/9 ) ( 5/8 ) = 35/1287

on the fourth attempt;

⇒  ( 8/13 ) ( 7/12) ( 6/11 ) ( 5/10 ) ( 4/9 ) ( 3/8 ) ( 2/7 ) ( 5/6 ) = 5/1287

so we add everything;  

⇒ 10/39 + 14/143 + 35/1287 + 5/1287

= 0.38539

Therefore, the probability that Jack draws the blue ball is 0.38539

hope it you

step-by-step explanation:

sin(7pi/6 - pi/3)  

= sin(7pi/6 - 2pi/6)  

= sin(5pi/6)  

= sin(pi - pi/6)  

= sin(pi/6)  

= 1/2  

sin 7pi/6 - sin pi/3  

= sin (pi + pi/6) - sin pi/3  

= -sin pi/6 - sin pi/3  

= -1/2 - sqrt(3)/2  

= -(1+sqrt(3))2