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Finding the Fourth Proportional to 217.68, 300.40 and 129.20

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Solution

The fourth proportional to 217.68, 300.40 and 129.20 is: 178.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    217.68 : 300.40 = 129.20 : x
  2. Step 2: Convert to fraction form
    217.68/300.40 = 129.20/x
  3. Step 3: Cross multiply
    217.68x = 300.40 × 129.20
  4. Step 4: Simplify right side
    217.68x = 38,811.68
  5. Step 5: Solve for x
    x = 38,811.68/217.68
  6. Step 6: Final answer
    x = 178.30

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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.