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Finding the Fourth Proportional to 100.79, 139.11 and 84.39

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Solution

The fourth proportional to 100.79, 139.11 and 84.39 is: 116.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.79 : 139.11 = 84.39 : x
  2. Step 2: Convert to fraction form
    100.79/139.11 = 84.39/x
  3. Step 3: Cross multiply
    100.79x = 139.11 × 84.39
  4. Step 4: Simplify right side
    100.79x = 11,738.80
  5. Step 5: Solve for x
    x = 11,738.80/100.79
  6. Step 6: Final answer
    x = 116.47

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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.