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Finding the Fourth Proportional to 72.50, 108.57 and 39.90

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Solution

The fourth proportional to 72.50, 108.57 and 39.90 is: 59.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.50 : 108.57 = 39.90 : x
  2. Step 2: Convert to fraction form
    72.50/108.57 = 39.90/x
  3. Step 3: Cross multiply
    72.50x = 108.57 × 39.90
  4. Step 4: Simplify right side
    72.50x = 4,331.94
  5. Step 5: Solve for x
    x = 4,331.94/72.50
  6. Step 6: Final answer
    x = 59.75

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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.