Question

There is a bag with only red marbles and blue marbles.
The probability of randomly choosing a red marble is
7/10th

There are 42 red marbles in the bag and each is equally likely to be chosen.
Work out how many marbles in total there must be.

Answer 1

Answer:

if the probability of picking a red marble from a jar that contains 4 red marbles and 6 blue marbles is 4/10 or 2/5, then the probability of not picking a red marble is equal to 1 - 4/10 = 6/10 or 3/5, which is also the probability of picking a blue marble.