Question

A bag contains white, black and red balls only. A ball is drawn at random from the bag. The probability of getting a white ball is 3/10 and that of a black ball is 2/5. Find the probability of getting a red ball. If the bag contains 20 black balls, then find the total number of balls in the bag

NCERT Class X
Mathematics - Exemplar Problems

Chapter _QUESTION PAPER SET 12

Answer 1

probability of getting a red ball is 15/50and the total number of balls in the bag are 50. because          we have to assume that total number of balls in the bag as X. they said that total black balls in the bag are 20.so according to problem probability of taking a black ball is   20/X=2/5 ⇒X=50.then total number of balls in bag are 50.and again they said that probability of getting white ball is 3/10. assume that probability of getting white ball as Y. then probability of taking white ball is  Y/50=3/10⇒Y=15  TOTAL NUMBER OF BALLS IN BAG = NUMBER OF WHITE BALLS +NUMBER OF BLACK BALLS +NUMBER OF RED BALLS

50=15+20+number of red balls

50-35=number of red balls

number of red balls =15

probability of getting a red ball is 15/50

Answer 2

GOOD EVENING FRIEND

Probability of getting a red ball is 15/50and the total number of balls in the bag are 50. because          we have to assume that total number of balls in the bag as X. they said that total black balls in the bag are 20.so according to problem probability of taking a black ball is   20/X=2/5 ⇒X=50.then total number of balls in bag are 50.and again they said that probability of getting white ball is 3/10. assume that probability of getting white ball as Y. then probability of taking white ball is  Y/50=3/10⇒Y=15  TOTAL NUMBER OF BALLS IN BAG = NUMBER OF WHITE BALLS +NUMBER OF BLACK BALLS +NUMBER OF RED BALLS

50=15+20+number of red balls

50-35=number of red balls

number of red balls =15

probability of getting a red ball is 15/50

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