Multiple choice

A bag contains $15$ red, $8$ blue and several green marbles. A marble is selected at random. The probability of drawing a blue marble is $\dfrac {1}{5}$. $5$ green marbles are now taken out from the bag. If a marble is now drawn at random, find the probability of drawing a green marble

  1. $\dfrac {3}{10}$
  2. $\dfrac {12}{35}$
  3. $\dfrac {23}{40}$
  4. $\dfrac {17}{35}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Initial blue probability 1/5 = 8/(15+8+G), so 15+8+G = 40, G = 17. After removing 5 green marbles, green count is 12 and total is 35. Probability of green is 12/35.

AI explanation

Since the probability of drawing a blue marble is 1/5, the total number of marbles is 8 divided by 1/5, which equals 40 marbles. This means there are 40 minus 15 minus 8, leaving 17 green marbles. After taking out 5 green marbles, there are 12 green marbles left out of a new total of 35 marbles. The result is 12/35.

Keep practicing — related questions