Question

On a number line, point D is at -3, and point E is at 6. The point F lies on DE. The ratio of DF to FE is 2:3. Where does point F lie on the number line?

Answer 1

Answer: point F is at   0.6   on the number line

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Explanation:

The ratio 2:3 scales up to 2x:3x for some positive real number x.

This means the distance from D to F is 2x units, and the distance from F to E is 3x units. Combine those two smaller distances to get 2x+3x = 5x to represent the full distance from D to E.

D is at -3 and E is at 6. This is a distance of 9 units since |-3-6| = |-9| = 9

Set this equal to the 5x from earlier and solve

5x = 9

x = 9/5

x = 1.8

This leads to 2x = 2*1.8 = 3.6

Therefore, we'll move 3.6 units from -3 to -3+3.6 = 0.6 which is the location of point F on the number line.

Notice that from 0.6 to 6 is 5.4 units and that 3x = 3*1.8 = 5.4 matches up to help confirm the answer.