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Finding the Fourth Proportional to 129.42, 178.60 and 71.20

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Solution

The fourth proportional to 129.42, 178.60 and 71.20 is: 98.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.42 : 178.60 = 71.20 : x
  2. Step 2: Convert to fraction form
    129.42/178.60 = 71.20/x
  3. Step 3: Cross multiply
    129.42x = 178.60 × 71.20
  4. Step 4: Simplify right side
    129.42x = 12,717.10
  5. Step 5: Solve for x
    x = 12,717.10/129.42
  6. Step 6: Final answer
    x = 98.26

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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.