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Finding the Fourth Proportional to 39.90, 59.91 and 30.87

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Solution

The fourth proportional to 39.90, 59.91 and 30.87 is: 46.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.90 : 59.91 = 30.87 : x
  2. Step 2: Convert to fraction form
    39.90/59.91 = 30.87/x
  3. Step 3: Cross multiply
    39.90x = 59.91 × 30.87
  4. Step 4: Simplify right side
    39.90x = 1,849.42
  5. Step 5: Solve for x
    x = 1,849.42/39.90
  6. Step 6: Final answer
    x = 46.35

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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.