Tactic 11: Be Careful About Units

PAY ATTENTION!!! Often questions will be asked using one set of units, but answers must be given using a different type of units. For example: A question refers to a piece of wood 12 feet long but then asks you for a related answer in yards The WRONG answer is almost always a choice. Be careful about units!!!

Example 11.1 At a speed of 48 miles per hour, how many minutes will be required to drive 32 miles? A) 2/3B) 3/2C) 40 D) 45E) 2400 Notice that the problem using HOURS but asks for an answer in MINUTES!

Example 11.1 (continued) Start by setting up a proportion: HOURS! C: 40

Example 11.2 The wholesale price of potatoes is usually 3 pounds for $1.79. How much money, in cents, did a restaurant save when it was able to purchase 600 pounds of potatoes at 2 pounds for $1.15 ? Notice the problem gives you prices in dollars but asks you for the answer in cents.

Example 11.2 (continued) First, calculate how much the restaurant would save in dollars. Next, convert answer to cents. 1300

Example 11.3 A 2.25 pound bag of pistachio nuts costs $6.00. At this rate, what is the cost, in cents, of a bag weighing 9 ounces? (Note: 1 pound = 16 ounces) A) 1.5B) 24C) 150D) 1350 E) 2400 Notice TWO Conversions in this problem: Problem = Pounds Answer = ounces Problem = DollarsAnswer = cents

Example 11.3 (continued) First : Next: Finally: C: 150

IN CONCLUSION ALWAYS PAY ATTENTION TO UNITS! Make sure your answer is the right TYPE of answer. Be especially careful on multiple choice problems which will have reasonably wrong answers.