Brain Teasers
Cressida
Cressida didn't like to tell her age, so when she was asked, her mother answered for her. Her mother said, "I'm just seven times as old as she is now. In twenty years, she'll be just half the age that I will be then."
How old is clever little Cressida?
How old is clever little Cressida?
Answer
Cressida is four years old.Hide Answer Show Answer
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Comments
Cressida isn't clever, her mom is. Cressida is only very shy. No big deal, just clarifying.
@ gakuka
I was going to make a similar comment, gak!
I'm sure some people will do this as an algebra problem, but it's easier than that.
20 is (1/2 - 1/7) / (1/2) = 5/7 of how old Cressida's mom is now, so her mom is 7/5 * 20 = 28 and Cressida is 28/7 = 4.
Less than 10 seconds in my head.
20 is (1/2 - 1/7) / (1/2) = 5/7 of how old Cressida's mom is now, so her mom is 7/5 * 20 = 28 and Cressida is 28/7 = 4.
Less than 10 seconds in my head.
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