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Finding the Fourth Proportional to 128.96, 178.08 and 100.04

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Solution

The fourth proportional to 128.96, 178.08 and 100.04 is: 138.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.96 : 178.08 = 100.04 : x
  2. Step 2: Convert to fraction form
    128.96/178.08 = 100.04/x
  3. Step 3: Cross multiply
    128.96x = 178.08 × 100.04
  4. Step 4: Simplify right side
    128.96x = 17,815.12
  5. Step 5: Solve for x
    x = 17,815.12/128.96
  6. Step 6: Final answer
    x = 138.14

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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.