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Finding the Fourth Proportional to 100.85, 139.23 and 80.21

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Solution

The fourth proportional to 100.85, 139.23 and 80.21 is: 110.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.85 : 139.23 = 80.21 : x
  2. Step 2: Convert to fraction form
    100.85/139.23 = 80.21/x
  3. Step 3: Cross multiply
    100.85x = 139.23 × 80.21
  4. Step 4: Simplify right side
    100.85x = 11,167.99
  5. Step 5: Solve for x
    x = 11,167.99/100.85
  6. Step 6: Final answer
    x = 110.74

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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.