CHALLENGE

GRADE  9-12 / Age 14+

There is just something about the number 75....

1)  What carat gold is 75 percent pure?

2)  75 in base ten is the same as 300 in base b.  Find b.

3)  The array of

4  9  2

3  5  7

8  1  6

is a magic square whose rows, columns, and diagonals all sum to 15. Convert it into a magic square whose rows, columns, and diagonals all sum to 75.

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