Football Passing Data Sufficiency

XAT 2024 · Quantitative Ability & Data Interpretation · Medium · Data Sufficiency

A group of boys is practising football in a rectangular ground. Raju and Ratan are standing at the two opposite mid-points of the two shorter sides. Raju has the ball, who passes it to Rivu, who is standing somewhere on one of the longer sides. Rivu holds the ball for 3 seconds and passes it to Ratan. Ratan holds the ball for 2 seconds and passes it back to Raju. The path of the ball from Raju to Rivu makes a right angle with the path of the ball from Rivu to Ratan. The speed of the ball, whenever passed, is always 10 metre per second, and the ball always moves on straight lines along the ground.

Consider the following two additional pieces of information: I. The dimension of the ground is 80 metres ×\times 50 metres. II. The area of the triangle formed by Raju, Rivu and Ratan is 1000 square metres.

Consider the problem of computing the following: how many seconds does it take for Raju to get the ball back since he passed it to Rivu? Choose the correct option.

  1. A.

    I alone is sufficient to solve the problem.

  2. B.

    II alone is sufficient to solve the problem.

  3. C.

    Either of I or II, by itself, is sufficient to solve the problem.

  4. D.

    I and II both are required to solve the problem.

  5. E.

    The problem cannot be solved even with both I and II.

Answer

A

Explanation

Let Raju be AA, Ratan be BB, and Rivu be CC. AA and BB are midpoints of shorter sides of length ww, so AB=LAB = L (the length of the ground). Triangle ACBACB is right-angled at CC. Since CC lies on a longer side, the perpendicular distance from CC to ABAB is w/2w/2. Using Statement I: L=80L = 80, w=50w = 50. AB=80AB = 80. In right triangle ACBACB, AC2+BC2=AB2=802=6400AC^2 + BC^2 = AB^2 = 80^2 = 6400. Area of ΔACB=12×base×height=12×80×25=1000\Delta ACB = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 80 \times 25 = 1000. Also, Area =12xy=1000  ⟹  xy=2000= \frac{1}{2} x y = 1000 \implies xy = 2000. (x+y)2=x2+y2+2xy=6400+4000=10400  ⟹  x+y=2026(x+y)^2 = x^2 + y^2 + 2xy = 6400 + 4000 = 10400 \implies x+y = 20\sqrt{26}. Total distance traveled by the ball =x+y+80=2026+80= x + y + 80 = 20\sqrt{26} + 80. Time taken =x+y+8010+3+2= \frac{x+y+80}{10} + 3 + 2, which can be uniquely determined. Thus, Statement I alone is sufficient. Statement II alone gives area = 1000, which gives xy=2000xy = 2000, but without knowing ABAB (or x2+y2x^2 + y^2), we cannot find x+y+ABx+y+AB. Hence, Statement I alone is sufficient.

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