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Finding the Fourth Proportional to 431.22, 646.86 and 138.74

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Solution

The fourth proportional to 431.22, 646.86 and 138.74 is: 208.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.22 : 646.86 = 138.74 : x
  2. Step 2: Convert to fraction form
    431.22/646.86 = 138.74/x
  3. Step 3: Cross multiply
    431.22x = 646.86 × 138.74
  4. Step 4: Simplify right side
    431.22x = 89,746.80
  5. Step 5: Solve for x
    x = 89,746.80/431.22
  6. Step 6: Final answer
    x = 208.13

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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.