16Hit1600
AlgebraHardValue on a line between two known points

Algebra practice question

In the xy-plane, a line passes through (1, 2) and (7, 10). What is the y-coordinate of the point on the line whose x-coordinate is 4?

Answer: 6

Slope: (10 − 2)/(7 − 1) = 4/3. From x = 1 to x = 4 is 3 units, so y rises by 4: 2 + 4 = 6. (x = 4 is the midpoint of 1 and 7, so y is the midpoint of 2 and 10.)

Common wrong answers

If you answered 4
4 repeats the x-coordinate.
If you answered 8
8 is the rise from x = 1 to x = 7, not the y-value at x = 4.
If you answered 5.33
5.33 is 4 × 4/3, the rise from x = 0 rather than from x = 1, without adding the starting y.

More Algebra questions

Not affiliated with the College Board. SAT is a trademark of the College Board.