Posted by **Tao** on Sunday, December 13, 2009 at 12:36pm.

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.

- Math -
**Marth**, Sunday, December 13, 2009 at 4:26pm
"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.

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