Difficulty: Easy
Correct Answer: 1/5
Explanation:
Introduction / Context: This question tests the slope formula for a line passing through two given points. Slope measures the rate of change of y with respect to x and is computed as “rise over run.” In coordinate geometry and aptitude, accurately substituting into the slope formula is essential, and simplifying the resulting fraction correctly is a common requirement.
Given Data / Assumptions:
Concept / Approach: Use the slope formula: m = (y2 - y1) / (x2 - x1). Any consistent order works as long as you subtract y and x in the same order. Then simplify the fraction. The sign of the slope indicates whether the line rises or falls as x increases.
Step-by-Step Solution: 1) Identify (x1, y1) = (8, 2) and (x2, y2) = (3, 1) 2) Apply the slope formula: m = (y2 - y1) / (x2 - x1) 3) Substitute values: m = (1 - 2) / (3 - 8) 4) Compute differences: 1 - 2 = -1 3 - 8 = -5 5) Divide: m = (-1)/(-5) = 1/5
Verification / Alternative check: A quick interpretation check: moving from x = 3 to x = 8 increases x by 5 while y increases from 1 to 2, which is an increase of 1. So rise/run = 1/5, matching the computed slope. The slope is positive, which makes sense because y increases as x increases across these two points.
Why Other Options Are Wrong: • 5 is the reciprocal (run/rise) and not the slope. • 3/5 and 5/3 come from incorrect subtraction or mixing points. • -1/5 would happen if only one difference is made negative (inconsistent subtraction).
Common Pitfalls: • Subtracting y values in one order and x values in the opposite order. • Forgetting that negative divided by negative becomes positive.
Final Answer: 1/5
Discussion & Comments