Class 5G is having a pizza party. Mrs Baker asked all the children to bring in 50c for their share of the pizza.The next day all the girls came with their 50c but Mrs Baker noticed that every girl had brought their 50c using different coins.

Whatis the most number of girls that there could be in the class?

Figure out the number of different coin combinations that will add up to 50 cents. You will just have to make a list and count them. For example
1 50 cent piece
2 quarters
5 dimes
10 nickels
50 pennies
45 pennies and 1 nickel
40 pennies and 1 dime
40 pennies and 2 nickels
30 pennies and 2 dimes
30 pennies, 1 dime and 2 nickels
30 pennies and 4 nickels
25 pennies and 1 quarter
25 pennies and 5 nickels
25 pennies, 3 nickels and 1 dime
20 pennies and three dimes
20 pennies, two dimes and two nickels
etc. etc.

There is no simple formula to plug into and solve.

2 answers

16
The maximum number of girls that could be in the class is 16. In order to have all the girls bring their 50c using different coins, there must be 16 different coin combinations that add up to 50 cents. For example, one girl may bring 1 50 cent piece, another may bring 2 quarters, another may bring 5 dimes, and so on, until each girl has a unique combination of coins. There are exactly 16 different ways to make 50 cents using different coin combinations, hence the maximum number of girls in the class is 16.