Suppose that a defined population is all men who are 50 or younger and a survey is being conducted which of these is an example of selection bias

What the heck don’t understand

The great thing about this problem is they give you everything you need to solve it easily. so the expression is: 12h+30w12h+30wand so everywhere you have an “h” you place 66. and everywhere you have a “w” you place 33. then the expression will look like this: 12(66)+30(33)12(66)+30(33)from here you multiply and then add. getting the following of: $785,862hope this