Question

There is a bag with only red marbles and blue marbles.

The probability of randomly choosing a blue marble is 58.
There are 72 marbles in total in the bag and each is equally likely to be chosen.
Work out how many red marbles there must be.

Answer 1

14 red marbles

Important Note

The probability of choosing a blue marble is given as 58, but probabilities should be expressed as a value between 0 and 1. It seems there might be a misunderstanding or a typo in the question. However, assuming that the probability of choosing a blue marble is 58/72, we can proceed with the calculation.

Calculations

The probability of choosing a blue marble is 58/72. Since there are 72 marbles in total, we can calculate the number of blue marbles by multiplying the total number of marbles by the probability of choosing a blue marble:

• Number of blue marbles = Total marbles × Probability of choosing a blue marble
• Number of blue marbles = 72 × (58/72)

The 72 in the numerator and denominator cancel out, leaving:

• Number of blue marbles = 58

Now, to find the number of red marbles, we can subtract the number of blue marbles from the total number of marbles:

• Number of red marbles = Total marbles - Number of blue marbles
• Number of red marbles = 72 - 58
• Number of red marbles = 14

So, there must be 14 red marbles in the bag.

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