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A bag contains 5 red marbles, 8 blue marbles and 7 green marbles. If two marbles are drawn out of the bag, what is the exact probability that both marbles drawn will be blue?
Answer:

A bag contains 55 red marbles, 88 blue marbles and 77 green marbles. If two marbles are drawn out of the bag, what is the exact probability that both marbles drawn will be blue?\newlineAnswer:

Full solution

Q. A bag contains 55 red marbles, 88 blue marbles and 77 green marbles. If two marbles are drawn out of the bag, what is the exact probability that both marbles drawn will be blue?\newlineAnswer:
  1. Calculate Total Marbles: Determine the total number of marbles in the bag. The bag contains 55 red marbles, 88 blue marbles, and 77 green marbles. To find the total, we add these numbers together. 55 red ++ 88 blue ++ 77 green == 2020 total marbles.
  2. First Blue Marble Probability: Calculate the probability of drawing the first blue marble.\newlineThe probability of drawing a blue marble on the first draw is the number of blue marbles divided by the total number of marbles.\newlineProbability of first blue marble = Number of blue marbles / Total number of marbles = 820\frac{8}{20}.
  3. New Total Marbles: Determine the new total number of marbles after one blue marble has been drawn.\newlineAfter drawing one blue marble, there is one less blue marble and one less marble in total.\newlineNew total number of marbles = 201=1920 - 1 = 19 marbles.
  4. Second Blue Marble Probability: Calculate the probability of drawing a second blue marble after the first has been drawn.\newlineNow, there are 77 blue marbles left and 1919 marbles in total.\newlineProbability of second blue marble = Number of blue marbles left / New total number of marbles = 719\frac{7}{19}.
  5. Consecutive Events Probability: Calculate the probability of both events happening consecutively.\newlineTo find the probability of both marbles being blue, we multiply the probability of the first event by the probability of the second event.\newlineProbability of both blue marbles = Probability of first blue marble ×\times Probability of second blue marble = (8/20)×(7/19)(8/20) \times (7/19).
  6. Simplify Probability: Simplify the probability.\newline(820)×(719)=(25)×(719)=1495(\frac{8}{20}) \times (\frac{7}{19}) = (\frac{2}{5}) \times (\frac{7}{19}) = \frac{14}{95}.

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