Turning 3D Balls into 2D Is Easy

A bag contains 5 black balls, 4 white balls and 3 red balls. If a ball is selected randomwise the probability that it is black or red ball is a. 1/3 b. 1/4 c. /12 d. 2/3

A box contains 3 orange balls, 3 green balls and 2 blue balls. Three balls are drawn at random from the box without replacement. The probability of drawing 2 green balls and one blue ball is (167)/(168) b. 1/(28) c. 2/(21) d. 3/(28)

There are 30 white balls and 10 red balls in bag. 16 balls are drawn with replacement from the bag. If X be the number of white balls drawn then the value of ("mean"(X))/("standard deviation"(X)) is equal to (A) 4sqrt3 (B) 2sqrt3 (C) 3sqrt3 (D) 3sqrt2

A bag contains 5 black balls, 4 white balls and 3 red balls. If a ball is selected random wise, the probability that if is black or red balls is 1/3 b. 1/4 c. 5/(12) d. 2/3

A fair die is rolled. If face 1 turns up, a ball is drawn from Bag A. If face 2 or 3 turns up, a ball is drawn from Bag B. If face 4 or 5 or 6 turns up a ball is drawn from Bag C. Bag A contains 3 red and 2 white balls, Bag B contains 3 red and 4 white balls and Bag C contains 4 red and 5 white balls. The die is rolled, a Bag is picked up and a ball is drawn. If the drawn ball is red, what is the probability that it is drawn from Bag B?

Bag A contains 4 green and 3 red balls and bag B contains 4 red and 3 green balls.One bag is taken at random and a ball is drawn and noted it is green.The probability that it comes bag B is (A) 2/7 (B) 2/3 (C) 3/7 (D) 1/3

A wooden ball of density D is immersed in water of density d to a depth h//2 below the surface of water and then relased. To what height will the ball jump out of water ?

If the number of ways of selecting r balls with replcement out of n balls numbered 1,2,3……,100 such that the largest number selected is 10 is 271, then r= (A) 4 (B) 5 (C) 3 (D) none of these