Inclusive Numbers

Read the following SAT test question and then select your answer.

The Knowsys Method starts with reading carefully. This is the most important step because misreading will very frequently lead students to the wrong answer. After you read, note the bottom line and assess your options. Always ask two questions: "What could I do?" and "What should I do?" The first question reminds you to look into your "toolbox" for formulas, strategies, and tricks that might help with the problem. The second leads you to the most efficient way to solve the problem. Once you have selected a method, attack the problem! Then loop back to the top the check your answer against the bottom line.

On the last day of a one-week sale, customers numbered 149 through 201 were waited on. How many customers were waited on that day?

The hardest thing abut this problem is how easy it is. Read carefully: the bottom line is the number of customers waited on during Day 7 of the sale. Note this at the top of your work.

Day 7=


Next ask, "What could I do?" Since customers 149 through 201 were waited on, you could simply subtract these two numbers. "What should I do?" There is no faster way to solve this problem than a single subtraction step, so attack!

201 - 149 = 52

Now loop back. Is 52 the number of people waited on? Actually, it is not. Subtracting 149 from 201 does not include customer 149. These are inclusive numbers, so you need to add 1 to account for the first person, item, or object.

(201 - 149) + 1 = 53

Now look at the answer choices.

A) 51

B) 52

C) 53

D) 152

E) 153

The answer is C.


On sat.collegeboard.org, 50% of responses to this question were correct.


Want more help with math? Visit www.myknowsys.com!