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Finding the Fourth Proportional to 129.21, 178.34 and 90.38

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Solution

The fourth proportional to 129.21, 178.34 and 90.38 is: 124.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.21 : 178.34 = 90.38 : x
  2. Step 2: Convert to fraction form
    129.21/178.34 = 90.38/x
  3. Step 3: Cross multiply
    129.21x = 178.34 × 90.38
  4. Step 4: Simplify right side
    129.21x = 16,117.03
  5. Step 5: Solve for x
    x = 16,117.03/129.21
  6. Step 6: Final answer
    x = 124.74

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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.