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Finding the Fourth Proportional to 100.81, 139.06 and 65.85

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Solution

The fourth proportional to 100.81, 139.06 and 65.85 is: 90.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.81 : 139.06 = 65.85 : x
  2. Step 2: Convert to fraction form
    100.81/139.06 = 65.85/x
  3. Step 3: Cross multiply
    100.81x = 139.06 × 65.85
  4. Step 4: Simplify right side
    100.81x = 9,156.75
  5. Step 5: Solve for x
    x = 9,156.75/100.81
  6. Step 6: Final answer
    x = 90.84

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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.