How to Make Things Faster

Chapter 97. Mrs. Utley

Mrs. Utley was my third-grade teacher when I was about nine years old. She taught us capacity planning. Here’s one of the problems we worked on:

Imagine that you have $1. Write three ways you could buy items from the list below, leaving at least 25¢ in change. Write down how much change you have left.

Item	Price
Soda pop	15¢
Candy bar	10¢
Bubble gum	1¢

My answers would have looked something like this one:

Item	Qty	Price	Total
Soda pop	2	15¢	30¢
Candy bar	4	10¢	40¢
Total			70¢
Change			30¢

It was a clever problem to help train us for transactions that would happen nearly every day for the rest of our lives. To do the problem:

• We had to grok the overall concept of trading one resource for another.

• We had to convert between $ (the unit for the stuff we had) and ¢ (the unit for the stuff we wanted).

• We had to add and subtract—and multiply, if we wanted to finish earlier.

• We had to formulate a way to communicate our answer back to the teacher so she could use the information. (Her particular use was to evaluate how well we had learned to do the problem.)

These are exactly the things you have to know, to do capacity planning.