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Finding the Fourth Proportional to 431.76, 646.35 and 408.78

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Solution

The fourth proportional to 431.76, 646.35 and 408.78 is: 611.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.76 : 646.35 = 408.78 : x
  2. Step 2: Convert to fraction form
    431.76/646.35 = 408.78/x
  3. Step 3: Cross multiply
    431.76x = 646.35 × 408.78
  4. Step 4: Simplify right side
    431.76x = 264,214.95
  5. Step 5: Solve for x
    x = 264,214.95/431.76
  6. Step 6: Final answer
    x = 611.95

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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.