There are 720 boys and 700 girls in a school. The probability that a boy chosen at random studies French is 2/3 The probability that a girl chosen at random studies French is 3/5. Work out the number of students in the school who study French.

The probability that a boy chosen at random studies French is 2/3. This is also a proportion. It says that for every 3 boys, you can say that 2 of them will study french. It is also close to 66% as it can be viewed as a percentage. This means that if you have the total number of boys you will be able to work out how many of them studied french. In this case, 720 boys. 720 x (2/3) = 480 boys that study French.
We can do this for the girls too. 700 girls x (3/5) = 400 girls that study French. If we add both of these results we will get the total number of students that study French. 400+480 = 900. The answer is 900.