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Finding the Fourth Proportional to 57.18, 78.80 and 39.69

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Solution

The fourth proportional to 57.18, 78.80 and 39.69 is: 54.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.18 : 78.80 = 39.69 : x
  2. Step 2: Convert to fraction form
    57.18/78.80 = 39.69/x
  3. Step 3: Cross multiply
    57.18x = 78.80 × 39.69
  4. Step 4: Simplify right side
    57.18x = 3,127.57
  5. Step 5: Solve for x
    x = 3,127.57/57.18
  6. Step 6: Final answer
    x = 54.70

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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.