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Finding the Fourth Proportional to 100.75, 139.05 and 61.42

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Solution

The fourth proportional to 100.75, 139.05 and 61.42 is: 84.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.75 : 139.05 = 61.42 : x
  2. Step 2: Convert to fraction form
    100.75/139.05 = 61.42/x
  3. Step 3: Cross multiply
    100.75x = 139.05 × 61.42
  4. Step 4: Simplify right side
    100.75x = 8,540.45
  5. Step 5: Solve for x
    x = 8,540.45/100.75
  6. Step 6: Final answer
    x = 84.77

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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.