There are only 7 blue pens, 4 green pens and 6 red pens in a box. One pen is taken at random from the box. Write down the probability that this pen is blue.

The probability is the likelihood of an event occurring.In this case, 1 pen is being taken out of a bag of; 7 blue pens, 4 green pens and 6 red pens. This means 1 out of 17 (7+4+6) pens will be taken.We are asked to work out the probability this 1 pen is blue. We know there are 7 blue pens in the bag, out of 17 pens in total in the bag. Therefore the probability that a blue pen is picked is 7(blue pens)/17(total pens) = 7/17