Actually Applicable Application Problems and Brainteasers/Tipping

Overview
Information about tipping in general is included in the Tip Estimation 1 Problem.

Now that calculators are so easy to carry with you (and in fact included as apps in devices you need for other reasons), many people prefer to calculate tips exactly (then perhaps round afterward).

General Method
Choose the tip percentage you want to give.

Convert that percentage to a decimal. For example, 20% is 0.2 (if it helps you to write it as 0.20 that's OK too) and 15% is 0.15.

Multiply the bill for the meal by that decimal. The product is how much you should tip. (You can round at this point if you wish.)

Problems
Calculate the tip on these bills at 15%, 20%, and 25%:


 * $23.47
 * $32.50
 * $19.45

Extension 1: Planning
If a server needs to earn $150 in tips and the average bill in a restaurant is $25, approximately how many tables must he wait on?

Extension 2: Evaluating Estimates
Compare your exact results from this method with at least two methods for estimating a tip, and use that to help you form an opinion about estimation methods.

Make Your Own Problem
Next time you eat out, use this method out to calculate a tip.