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Finding the Fourth Proportional to 128.90, 178.08 and 101.18

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Solution

The fourth proportional to 128.90, 178.08 and 101.18 is: 139.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.90 : 178.08 = 101.18 : x
  2. Step 2: Convert to fraction form
    128.90/178.08 = 101.18/x
  3. Step 3: Cross multiply
    128.90x = 178.08 × 101.18
  4. Step 4: Simplify right side
    128.90x = 18,018.13
  5. Step 5: Solve for x
    x = 18,018.13/128.90
  6. Step 6: Final answer
    x = 139.78

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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.