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Finding the Fourth Proportional to 71.78, 107.76 and 66.38

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Solution

The fourth proportional to 71.78, 107.76 and 66.38 is: 99.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.78 : 107.76 = 66.38 : x
  2. Step 2: Convert to fraction form
    71.78/107.76 = 66.38/x
  3. Step 3: Cross multiply
    71.78x = 107.76 × 66.38
  4. Step 4: Simplify right side
    71.78x = 7,153.11
  5. Step 5: Solve for x
    x = 7,153.11/71.78
  6. Step 6: Final answer
    x = 99.65

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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.