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Finding the Fourth Proportional to 66.78, 92.14 and 39.15

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Solution

The fourth proportional to 66.78, 92.14 and 39.15 is: 54.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.78 : 92.14 = 39.15 : x
  2. Step 2: Convert to fraction form
    66.78/92.14 = 39.15/x
  3. Step 3: Cross multiply
    66.78x = 92.14 × 39.15
  4. Step 4: Simplify right side
    66.78x = 3,607.28
  5. Step 5: Solve for x
    x = 3,607.28/66.78
  6. Step 6: Final answer
    x = 54.02

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.