Question

Half the pupils in Mrs. Cross's class are boys. Half the boys have blue eyes. Half the blue-eyed boys have blond hair. There are three boys with blue eyes and blond hair in Mrs.Crooss's class. How many pupils are there total in that class.

Answer 1

"There are three boys with blue eyes and blond hair in Mrs.Cross's class."

Start with 3.

"Half the blue-eyed boys have blond hair."

So the above number of 3 only represents half of the blue-eyed boys.

So, there are 2*3 blue-eyed boys total, which is 6.

"Half the boys have blue eyes."

Now we can determine that there are 6*2 boys total.



Try to determine how many pupils are in the class.

Answer 2

24