Four Strategies for Tackling Scale Problems on the CA Surveying Exam

Table of Contents

1. Know the difference between a large scale and a small scale

2. Study the units in the problem statement and the solution

3. Notice when units are missing

4. Know what "scale factor" means

1. Know the difference between a large scale and a small scale 

I'll just state this upfront: 1/10 is a larger scale than 1/100. Write that down somewhere, so you never get confused again! The worst part of this exam for me was memorizing conventions like that. This will come up both directly and indirectly in questions. For example, maybe you've determined that the scale required to fit a map on a sheet of paper is 1/44 and the problem asks for the largest scale that can be used, rounded to the nearest 10. The answer would be 1/50, because 1/40 would be too large and 1/60 would be too small. 

2. Study the units in the problem statement and the solution 

A very common "trick" on the exam is to give you a linear scale (so 1:10), and then ask for the measurement of a rectangular area. You'll have to apply the scale factor twice because the units considered are changing from linear to square. For example, if the rectangle is 2" x 3" on the paper, the area isn't just 6 square inches *10 (=60), it's 2*10 x 3*10 = 600. This can definitely get you if you're moving too quickly on the exam, so look out for these. 

3. Notice when units are missing

As in the example above, the scale is given as 1:10. When the units are not given in a scale, you can assume that the units are the same. For example, 1 inch = 10 inches, 1 mile = 10 miles. Sometimes the problem statement can be written in a misleading way, so make sure to recognize when the units are missing. 

4. Know what "scale factor" means

You'll sometimes see a problem state, "the scale factor is x" and the measured distance is y, what is the real distance? For me, it can be tricky to remember if you're supposed to multiply or divide by the scale factor, so jot down this formula on your cheat sheet: real distance = measured distance *x 

School of PE offers comprehensive exam review courses for the CA Seismic and CA Surveying exams. Visit our website to register for a prep class that best fits your schedule. 

About the Author: Erin E. Kelly

Ms. Kelly is an experienced structural engineer with a focus on seismic risk. She has extensive experience in structural failure investigations, seismic structural design, and seismic risk assessments. Through the School of P.E., she has taught a 32-hour course for the California Seismic P.E. Exam, authored several blog posts, and contributed to other review products. She has a Bachelor of Science in Civil Engineering from Johns Hopkins University and a Masters of Engineering in Structural Engineering from Lehigh University.