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Finding the Fourth Proportional to 78.18, 117.13 and 66.71

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Solution

The fourth proportional to 78.18, 117.13 and 66.71 is: 99.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.18 : 117.13 = 66.71 : x
  2. Step 2: Convert to fraction form
    78.18/117.13 = 66.71/x
  3. Step 3: Cross multiply
    78.18x = 117.13 × 66.71
  4. Step 4: Simplify right side
    78.18x = 7,814.11
  5. Step 5: Solve for x
    x = 7,814.11/78.18
  6. Step 6: Final answer
    x = 99.95

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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.