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Finding the Fourth Proportional to 78.69, 118.23 and 66.81

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Solution

The fourth proportional to 78.69, 118.23 and 66.81 is: 100.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.69 : 118.23 = 66.81 : x
  2. Step 2: Convert to fraction form
    78.69/118.23 = 66.81/x
  3. Step 3: Cross multiply
    78.69x = 118.23 × 66.81
  4. Step 4: Simplify right side
    78.69x = 7,898.95
  5. Step 5: Solve for x
    x = 7,898.95/78.69
  6. Step 6: Final answer
    x = 100.38

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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.