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Brainteasers

Puzzles to test mathematical skills, set by Anita Straker. Solutions below

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PREHISTORIC MONSTER

The fossil of an argentinosaurus is 37 metres long.

Its tail is twice as long as its neck, and its body is 2 metres longer than half its neck.

How long are the neck, body and tail of the fossil of the argentinosaurus?

AGES TO AGES

In 2001, Ben's dad was four times as old as Ben.

In 2005, his dad will be three times as old as Ben.

In what year will Ben's dad be twice as old as Ben?

SOLUTIONS Prehistoric monster (ages 7 to 11) 10 metres, 7 metres and 20 metres. Ages and ages (ages 11 to 14) 2017. Assume Ben was x years old in 2001, so his father was 4x in 2001. In 2005, Ben will be x + 4 , and his dad will be 4x + 4. So 3(x + 44x + 4, giving x = 8. Assume that Ben's dad will be twice as old as Ben in y years from 2001. 2(8 + y32 + y, so y = 16. Ben's dad will be twice as old as Ben in 2017.

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