Hi, This is my question:

The prob of 20 year 9 students to have a swimming pool is 0.2.

If they have a swimming pool the prob that they swim is 0.7.

Draw a tree diagram.

Find the prob of the year that swim.

would i do this?

then would i do 0.7 X 0.3= 0.21?

would this be corrects? if not where am i going wrong?