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Finding the Fourth Proportional to 86.61, 129.85 and 45.42

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Solution

The fourth proportional to 86.61, 129.85 and 45.42 is: 68.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.61 : 129.85 = 45.42 : x
  2. Step 2: Convert to fraction form
    86.61/129.85 = 45.42/x
  3. Step 3: Cross multiply
    86.61x = 129.85 × 45.42
  4. Step 4: Simplify right side
    86.61x = 5,897.79
  5. Step 5: Solve for x
    x = 5,897.79/86.61
  6. Step 6: Final answer
    x = 68.10

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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.