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Finding the Fourth Proportional to 42.60, 58.80 and 28.78

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Solution

The fourth proportional to 42.60, 58.80 and 28.78 is: 39.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.60 : 58.80 = 28.78 : x
  2. Step 2: Convert to fraction form
    42.60/58.80 = 28.78/x
  3. Step 3: Cross multiply
    42.60x = 58.80 × 28.78
  4. Step 4: Simplify right side
    42.60x = 1,692.26
  5. Step 5: Solve for x
    x = 1,692.26/42.60
  6. Step 6: Final answer
    x = 39.72

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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.