SAT Math : How to find value with a number line

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : How To Find Value With A Number Line

Gre12

If the tick marks are equally spaced on the number line above, what is the average (arithmetic mean) of x, y, and z?

Possible Answers:

4

6

8

7

5

Correct answer:

6

Explanation:

First, we must find out by how much they are spaced by. It cannot be 1, since 4(4) = 16, which is too great of a step in the positive direction and exceeds the equal-spacing limit. 2 works perfectly, however, as 4(2) equals 8 and fits in line with the equal spacing.

Next, we can find the values of x and y since we are given a value of 6 for the third tick mark. As such, x (6 – 4) and y (6 – 2) are 2 and 4, respectively.

Finally, z is 4 steps away from y, and since each step has a value of 2, 2(4) = 8, plus the value that y is already at, 8 + 4 = 12 (or can simply count).

Finding the average of all 3 values, we get (2 + 4 + 12)/3 = 18/3 = 6.

Example Question #2 : How To Find Value With A Number Line

How many numbers 1 to 250 inclusive are cubes of integers?

Possible Answers:

4\(\displaystyle 4\)

7\(\displaystyle 7\)

5\(\displaystyle 5\)

6\(\displaystyle 6\)

8\(\displaystyle 8\)

Correct answer:

6\(\displaystyle 6\)

Explanation:

The cubes of integers from 1 to 250 are 1, 8, 27,64,125,216.

Example Question #1 : Other Number Line

Slide1

On the number line above, the tick marks are equally spaced. Which of the following expresses \(\displaystyle y\) in terms of \(\displaystyle x\)?

Possible Answers:

\(\displaystyle 3x + 2\)

\(\displaystyle 3x -2\)

\(\displaystyle -x -2\)

\(\displaystyle 4x-2\)

\(\displaystyle 2x\)

Correct answer:

\(\displaystyle 3x + 2\)

Explanation:

If \(\displaystyle 1\) is between \(\displaystyle x\) and \(\displaystyle y\) on the number line, then \(\displaystyle x=0\) and \(\displaystyle y=2\).

So \(\displaystyle 3x + 2\) must be correct because 

\(\displaystyle 3(0)+2 = 2\).

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