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Finding the Fourth Proportional to 465.12, 640.40 and 421.92

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Solution

The fourth proportional to 465.12, 640.40 and 421.92 is: 580.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    465.12 : 640.40 = 421.92 : x
  2. Step 2: Convert to fraction form
    465.12/640.40 = 421.92/x
  3. Step 3: Cross multiply
    465.12x = 640.40 × 421.92
  4. Step 4: Simplify right side
    465.12x = 270,197.57
  5. Step 5: Solve for x
    x = 270,197.57/465.12
  6. Step 6: Final answer
    x = 580.92

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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.