Relative speed with head start: A runs 1 3⁄8 times as fast as B. If A gives B a start of 120 m and they finish together, find the race distance (the winning post distance from A’s start).

Question

Solve this multiple-choice question and choose the correct option.

Curioustab · Accepted Answer

Introduction / Context:This problem is about equalizing finish times with a head start when one runner is faster by a known factor. Given Data / Assumptions: Speed ratio v_A : v_B = 11 : 8 Head start for B = 120 m They finish together Concept / Approach:Set equal times: distance/v_A = (distance − headstart)/v_B. Substitute the known ratio and solve for the distance. Step-by-Step Solution: Let D be race distance from A's start.D / (11k) = (D − 120) / (8k) ⇒ (8/11)D = D − 120D − (8/11)D = 120 ⇒ (3/11)D = 120 ⇒ D = 440 m Verification / Alternative check:Plug D = 440 to confirm both times equal: 440/(11k) vs. 320/(8k) = 40/k each. Why Other Options Are Wrong:Other distances do not satisfy the time equality for the given ratio. Common Pitfalls:Adding/subtracting speeds incorrectly or forgetting to subtract the head start from B’s running distance. Final Answer:440 m

Relative speed with head start: A runs 1 3⁄8 times as fast as B. If A gives B a start of 120 m and they finish together, find the race distance (the winning post distance from A’s start).

Answer

Explanation