posted by mel on .
Six hundred pennies are placed in a row. If every other penny is replaced by a nickel and every third coin is replaced by a quarter, what is the final value of the 600 coins?
600 pennies = $6.00
after replacement by a nickel, there are 300 pennies and 300 nickels.
Value = 300*0.01 + 300*0.05 = $18.00
Finally, the replacement by quarters every third coin means that one-third of the nickels and one-third of the pennies will be replaced by quarters.
Think of the replacement process: the first one encountered is a penny, the next one is a nickel, the third one is a penny, .....
In the end, there will be
200 nickels, and
Total value = 200(0.01+0.05+0.25)=$62.00