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Finding the Fourth Proportional to 39.60, 59.40 and 28.78

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Solution

The fourth proportional to 39.60, 59.40 and 28.78 is: 43.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.60 : 59.40 = 28.78 : x
  2. Step 2: Convert to fraction form
    39.60/59.40 = 28.78/x
  3. Step 3: Cross multiply
    39.60x = 59.40 × 28.78
  4. Step 4: Simplify right side
    39.60x = 1,709.38
  5. Step 5: Solve for x
    x = 1,709.38/39.60
  6. Step 6: Final answer
    x = 43.17

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.