Multiple choice

A box contains $40$ red and blue marbles. If a marble is drawn at random, the probability of picking a blue marble is $\dfrac {3}{8}$. Ansh takes out one red and nine blue marbles and then draws a marble at random. Find the probability of drawing a blue marble

  1. $\dfrac {4}{5}$
  2. $\dfrac {2}{5}$
  3. $\dfrac {7}{40}$
  4. $\dfrac {1}{5}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total marbles = 40. Blue = (3/8)*40 = 15. Red = 25. After removing 1 red and 9 blue: Total = 40 - 10 = 30. Blue = 15 - 9 = 6. Probability = 6/30 = 1/5.

AI explanation

Since the probability of picking a blue marble from 40 is 3/8, the initial number of blue marbles is 3/8 of 40, which is 15 blue marbles. After Ansh takes out 1 red and 9 blue marbles, there are 15 minus 9, leaving 6 blue marbles out of a new total of 30 marbles. Using the classical probability formula, the probability is 6 divided by 30. The result is 1/5.

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