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Finding the Fourth Proportional to 66.61, 99.78 and 39.61

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Solution

The fourth proportional to 66.61, 99.78 and 39.61 is: 59.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.61 : 99.78 = 39.61 : x
  2. Step 2: Convert to fraction form
    66.61/99.78 = 39.61/x
  3. Step 3: Cross multiply
    66.61x = 99.78 × 39.61
  4. Step 4: Simplify right side
    66.61x = 3,952.29
  5. Step 5: Solve for x
    x = 3,952.29/66.61
  6. Step 6: Final answer
    x = 59.33

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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.