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Finding the Fourth Proportional to 66.78, 100.18 and 39.78

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Solution

The fourth proportional to 66.78, 100.18 and 39.78 is: 59.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.78 : 100.18 = 39.78 : x
  2. Step 2: Convert to fraction form
    66.78/100.18 = 39.78/x
  3. Step 3: Cross multiply
    66.78x = 100.18 × 39.78
  4. Step 4: Simplify right side
    66.78x = 3,985.16
  5. Step 5: Solve for x
    x = 3,985.16/66.78
  6. Step 6: Final answer
    x = 59.68

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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.