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Finding the Fourth Proportional to 92.40, 139.12 and 81.63

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Solution

The fourth proportional to 92.40, 139.12 and 81.63 is: 122.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.40 : 139.12 = 81.63 : x
  2. Step 2: Convert to fraction form
    92.40/139.12 = 81.63/x
  3. Step 3: Cross multiply
    92.40x = 139.12 × 81.63
  4. Step 4: Simplify right side
    92.40x = 11,356.37
  5. Step 5: Solve for x
    x = 11,356.37/92.40
  6. Step 6: Final answer
    x = 122.90

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.