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Finding the Fourth Proportional to 42.40, 58.20 and 39.28

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Solution

The fourth proportional to 42.40, 58.20 and 39.28 is: 53.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.40 : 58.20 = 39.28 : x
  2. Step 2: Convert to fraction form
    42.40/58.20 = 39.28/x
  3. Step 3: Cross multiply
    42.40x = 58.20 × 39.28
  4. Step 4: Simplify right side
    42.40x = 2,286.10
  5. Step 5: Solve for x
    x = 2,286.10/42.40
  6. Step 6: Final answer
    x = 53.92

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.