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Finding the Fourth Proportional to 129.47, 178.69 and 74.21

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Solution

The fourth proportional to 129.47, 178.69 and 74.21 is: 102.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.47 : 178.69 = 74.21 : x
  2. Step 2: Convert to fraction form
    129.47/178.69 = 74.21/x
  3. Step 3: Cross multiply
    129.47x = 178.69 × 74.21
  4. Step 4: Simplify right side
    129.47x = 13,259.65
  5. Step 5: Solve for x
    x = 13,259.65/129.47
  6. Step 6: Final answer
    x = 102.41

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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.