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Finding the Fourth Proportional to 102.72, 141.60 and 100.80

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Solution

The fourth proportional to 102.72, 141.60 and 100.80 is: 138.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.72 : 141.60 = 100.80 : x
  2. Step 2: Convert to fraction form
    102.72/141.60 = 100.80/x
  3. Step 3: Cross multiply
    102.72x = 141.60 × 100.80
  4. Step 4: Simplify right side
    102.72x = 14,273.28
  5. Step 5: Solve for x
    x = 14,273.28/102.72
  6. Step 6: Final answer
    x = 138.95

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.