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Finding the Fourth Proportional to 92.40, 138.63 and 66.78

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Solution

The fourth proportional to 92.40, 138.63 and 66.78 is: 100.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.40 : 138.63 = 66.78 : x
  2. Step 2: Convert to fraction form
    92.40/138.63 = 66.78/x
  3. Step 3: Cross multiply
    92.40x = 138.63 × 66.78
  4. Step 4: Simplify right side
    92.40x = 9,257.71
  5. Step 5: Solve for x
    x = 9,257.71/92.40
  6. Step 6: Final answer
    x = 100.19

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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.