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Finding the Fourth Proportional to 431.19, 646.87 and 138.71

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Solution

The fourth proportional to 431.19, 646.87 and 138.71 is: 208.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.19 : 646.87 = 138.71 : x
  2. Step 2: Convert to fraction form
    431.19/646.87 = 138.71/x
  3. Step 3: Cross multiply
    431.19x = 646.87 × 138.71
  4. Step 4: Simplify right side
    431.19x = 89,728.78
  5. Step 5: Solve for x
    x = 89,728.78/431.19
  6. Step 6: Final answer
    x = 208.10

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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.