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Finding the Fourth Proportional to 100.90, 139.10 and 83.80

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Solution

The fourth proportional to 100.90, 139.10 and 83.80 is: 115.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.90 : 139.10 = 83.80 : x
  2. Step 2: Convert to fraction form
    100.90/139.10 = 83.80/x
  3. Step 3: Cross multiply
    100.90x = 139.10 × 83.80
  4. Step 4: Simplify right side
    100.90x = 11,656.58
  5. Step 5: Solve for x
    x = 11,656.58/100.90
  6. Step 6: Final answer
    x = 115.53

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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.