Tuesday, 1 September 2009

DAY 29
Sixteen pingpong balls are placed inside a square, wooden rack in 4 rows of 4 so that they are held firmly together. How many additional balls are required to complete a pyramid on top of the 16-ball foundation? How many more would be needed to raise the pyramid one level higher?

Answer:

9 + 4 + 1 = 14
To raise the pyramid one level, 25 balls would have to be placed under the 16. Another level would require 36 balls---each new bottom level being a perfect square.

DAY 30
How many brothers and sisters are there in a family in which each boy has as many sisters as brothers, but each of the girls has twice as many brothers as sisters?

Answer:

4 brothers and 3 sisters.....If the boys have as many brothers as sisters, then there must be 1 more boy in the family than the number of girls. So the possiblilites are 2 boys and 1 girl, 3 boys and 2 girls, 4 boys and 3 girls and so on. 4 boys and 3 girls satisfies the reqirement that each girl has twice as many brothers as sisters.

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