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Finding the Fourth Proportional to 39.87, 54.95 and 31.16

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Solution

The fourth proportional to 39.87, 54.95 and 31.16 is: 42.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.87 : 54.95 = 31.16 : x
  2. Step 2: Convert to fraction form
    39.87/54.95 = 31.16/x
  3. Step 3: Cross multiply
    39.87x = 54.95 × 31.16
  4. Step 4: Simplify right side
    39.87x = 1,712.24
  5. Step 5: Solve for x
    x = 1,712.24/39.87
  6. Step 6: Final answer
    x = 42.95

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.