Question

A bag has r red balls and b black balls. All balls are identical except for their colours. In a trial a ball is randomly drawn from the bag its colour is noted and the ball is placed back into the bag along with another ball of the same colour. Note that the number of balls in the bag will increase by one after the trial. A sequence of four such trials is conducted. Which one of the following choices gives the probability of drawing a red ball in the fourth trial? (a) r/r+b (b)r/ (r+b)+(r+1)/(r+b+1)+(r+2)/(r+b+2)+(r+3)/(r+b+3) (c) r/r+b+3 (d) r+3/r+b+3​

Answer 1

Answer:

b is correct

Step-by-step explanation:

ok my answer is correct or you can help me