Math CentralQuandaries & Queries


Question from michael, a parent:

What is the formula to calculate:
If 25 items are evenly spread over 7 days, but one day has 3 items less than the other days, what is the number if items for each of the remaining 6 days?


I can show you two ways to approach this problem.

Method 1:

You want to spread 25 item evenly over 7 days so divide 25 by 7 to see how many to asign to each day. $\frac{25}{7} = 3$ with a remainder so you can't quite assign 4 to each day. If you assign 4 to 6 of the days how many will you have for the seventh day?

Method 2:

Think of this as a number if items being evenly spread over 7 days and then on one of the days, 3 items are removed. The resulting number of items distributed on the 7 days is 25.

If $n$ is the number of items originall distributed to each of the 7 days then the process described above yields

\[7 n - 3 = 25.\]

Solve for $n.$ When you have found $n$ make sure you check that it works.


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