This bag had 35 green, some black and 3 red marbles. Reaching blindfolded, the probability of picking a red is 1/23. How many black marbles are there.

Answer 1

let B = the number of black marbles.

probability of drawing red:
3/(35 + 3 + B) = 1/23

3/(38 +B) = 1/23
69 = 38 + B

B = 31