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Finding the Fourth Proportional to 57.18, 78.91 and 31.31

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Solution

The fourth proportional to 57.18, 78.91 and 31.31 is: 43.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.18 : 78.91 = 31.31 : x
  2. Step 2: Convert to fraction form
    57.18/78.91 = 31.31/x
  3. Step 3: Cross multiply
    57.18x = 78.91 × 31.31
  4. Step 4: Simplify right side
    57.18x = 2,470.20
  5. Step 5: Solve for x
    x = 2,470.20/57.18
  6. Step 6: Final answer
    x = 43.20

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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.