PSAT Math Multiple-Choice Question 609: Answer and Explanation

Question: 609

A line in the xy-plane has a slope of and passes through the origin. Which of the following is a point on the line?

• A. (15, 10)
• B. (3, 5)
• C.
• D. (10, 6)

Correct Answer: D

Explanation:

(D) The answer choices are all positive, so let's come up with some of the positive points on the line. The line has a slope of and passes through the origin (thus has a y-intercept of 0). So the equation for the line is:

The line starts at the origin and goes up 3 units and to the right 5 units. So (5, 3) is a point. From there, the line goes up 3 more units and to the right 5 more units, so (10, 6) is also a point, which is choice (D).

Alternatively, you could have used the process of elimination by plugging in the x-coordinates of the answer choices to get the y-coordinate at that value of x.