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Finding the Fourth Proportional to 39.76, 54.86 and 31.16

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Solution

The fourth proportional to 39.76, 54.86 and 31.16 is: 42.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.76 : 54.86 = 31.16 : x
  2. Step 2: Convert to fraction form
    39.76/54.86 = 31.16/x
  3. Step 3: Cross multiply
    39.76x = 54.86 × 31.16
  4. Step 4: Simplify right side
    39.76x = 1,709.44
  5. Step 5: Solve for x
    x = 1,709.44/39.76
  6. Step 6: Final answer
    x = 42.99

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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.