Percent, Ratio and Arithmetic Word Problems
The topic E3n names first: arithmetic word problems, including every flavour of percent, ratio, proportion and rate the Upper Level test asks about.
5 topics · 23 questions
Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.
Percent and the Percent Equation
- How it worksHow does the sentence part is percent of whole turn straight into an equation you can solve?
- Worked exampleFind 35 percent of 240 with no calculator by breaking it into 10 percent chunks.
- Worked exampleWalk me through finding the whole when 18 turns out to be 45 percent of it.
- Common mistakeWhy isn't asking what percent of 40 is 30 the same question as asking what percent of 30 is 40?
Percent Change, Discount and Tax
- How it worksHow does a percent change always measure against the ORIGINAL amount rather than the new one?
- Worked exampleFind the final cost of a 60 dollar jacket marked down 25 percent and then taxed 8 percent.
- Worked exampleWalk me through the percent increase when a town grows from 250 people to 320.
- Common mistakeWhy isn't a 20 percent drop cancelled out by a 20 percent rise the very next day?
- Going furtherWhat happens to a price after three straight years of 10 percent increases stacked on each other?
Ratios and Proportions
- How it worksHow does a ratio turn into parts of a whole, so that 3 to 2 becomes 3/5 and 2/5?
- Worked exampleFind how to split 45 marbles between two jars in a 4 to 5 ratio.
- Worked exampleWalk me through solving 7/12 = x/30 by cross multiplying.
- Common mistakeWhy doesn't adding 2 to both halves of a 3 to 5 ratio leave the ratio unchanged?
- Going furtherWhat changes when a ratio has three parts instead of two, like 2 to 3 to 7?
Rates, Unit Rates and Distance-Rate-Time
- How it worksHow does the distance equals rate times time triangle let you solve for whichever one is missing?
- Worked exampleFind how long a 174 mile drive takes at a steady 58 miles per hour.
- Worked exampleWalk me through a unit rate problem where 7 notebooks cost 10.50 in dollars.
- Common mistakeWhy isn't the average speed for a round trip just the average of the two speeds?
Multi-Step Arithmetic Word Problems
- How it worksHow does drawing the quantities as bars turn a tangled word problem into one subtraction?
- Worked exampleFind the change from 50 in dollars after buying three shirts priced at 12.75 each.
- Worked exampleWalk me through scaling a recipe written for 6 people so that it feeds 15.
- Worked exampleFind each person's share when a bill of 84 in dollars plus an 18 percent tip is split four ways.
- Common mistakeWhy doesn't the word more in a word problem always mean you should add?
AP®, SAT® and PSAT/NMSQT® are trademarks registered by the College Board (PSAT/NMSQT® jointly with the National Merit Scholarship Corporation). ACT® is a registered trademark of ACT Education Corp. GRE® is a registered trademark of ETS. LSAT® is a registered trademark of the Law School Admission Council. MCAT® is a registered trademark of the Association of American Medical Colleges. ISEE® and SSAT® are registered trademarks of their owners. None of these organizations is affiliated with, or endorses, Jentoo.