maths
posted by Carolyn on .
Andrew has 7 20c coins and 5 50c coins in his piggy bank. What is the smallest number of coins he might have to shake out to be certain of having 2 50c coins?

I don't know what country you are in, but I am not aware of "20c coins."
To be4 absolutely certain of getting 2 50c coins, you would have to shake out 9 coins. This is assuming the worst scenario that all the 20c coins come out first.