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Finding the Fourth Proportional to 129.76, 194.78 and 91.40

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Solution

The fourth proportional to 129.76, 194.78 and 91.40 is: 137.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.76 : 194.78 = 91.40 : x
  2. Step 2: Convert to fraction form
    129.76/194.78 = 91.40/x
  3. Step 3: Cross multiply
    129.76x = 194.78 × 91.40
  4. Step 4: Simplify right side
    129.76x = 17,802.89
  5. Step 5: Solve for x
    x = 17,802.89/129.76
  6. Step 6: Final answer
    x = 137.20

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.