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Finding the Fourth Proportional to 90.72, 135.98 and 39.30

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Solution

The fourth proportional to 90.72, 135.98 and 39.30 is: 58.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.72 : 135.98 = 39.30 : x
  2. Step 2: Convert to fraction form
    90.72/135.98 = 39.30/x
  3. Step 3: Cross multiply
    90.72x = 135.98 × 39.30
  4. Step 4: Simplify right side
    90.72x = 5,344.01
  5. Step 5: Solve for x
    x = 5,344.01/90.72
  6. Step 6: Final answer
    x = 58.91

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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.