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Finding the Fourth Proportional to 100.70, 139 and 61.38

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Solution

The fourth proportional to 100.70, 139 and 61.38 is: 84.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.70 : 139 = 61.38 : x
  2. Step 2: Convert to fraction form
    100.70/139 = 61.38/x
  3. Step 3: Cross multiply
    100.70x = 139 × 61.38
  4. Step 4: Simplify right side
    100.70x = 8,531.82
  5. Step 5: Solve for x
    x = 8,531.82/100.70
  6. Step 6: Final answer
    x = 84.73

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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.