SAT Math Tutorial

Intro

This is question 6 from Lesson 1 of my book The Scholarly Unicorn’s SAT Math Advanced Guide.

Topic: Heart of Algebra
Subtopic: Solving Linear Equations
Level: 3

Sample Problem

Question source

L = 11 + 1.6M

One end of an elastic band is taped to the bottom of a ceiling fan. When an object of mass M kilograms is attached to the other end of the elastic band, the band stretches to a length of L centimeters as shown in the equation above. What is M when L = 13 ?

Solution

* Algebraic solution: We let L = 13 and solve for M.

13 = 11 + 1.6M
2 = 1.6M
M = 2/1.6 = 20/16 = 5/4 or 1.25.

Note: There are lots of words in this problem that are completely unnecessary. The question could have simply been asked as follows:

If L = 11 + 1.6M, what is M when L = 13 ?

The SAT often likes to artificially create a “real world” context which is not needed when solving the problem.

Here is a video solution for this problem:

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 Steve W Expert Math Tutor, SAT Instructor, And Author I am a math professor, author of more than 20 math test prep books, experienced math tutor, and expert in preparing students for standardized tests. I began tutoring students in mathematics when I was a sophomore in college. By the time I began college, I had already tutored more than 100 stude...
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