Multiple choice

Passage

Each of the questions below consists of a question and three statements given below it. You have to decide whether the data provided in the statements are sufficient to answer the question. Read all the three statements and give answer.

Find the time taken by pipe C to fill the tank? I. Pipe A, Pipe B and Pipe C together can fill a tank in 8 minutes. Efficiency of pipe A is double the efficiency of pipe D. II. Pipe A and pipe D together can complete the work in 10 days. III. Pipe B and pipe D together can complete the work in 12 days.

  1. Only I and III

  2. Only II and III

  3. All I, II and III

  4. Any two of the three

  5. I, II and III together are not sufficient
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let rates be a, b, c, d (in tanks per minute). From I: a+b+c = 1/8. From II: a+d = 1/10, so d = 1/10 - a. From III: b+d = 1/12. Substituting d from II into III: b + (1/10 - a) = 1/12, giving b = a - 1/60. From I: a + (a-1/60) + c = 1/8, so 2a + c = 1/8 + 1/60 = 17/120. We need all three statements to uniquely determine c, the rate of pipe C.

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