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Finding the Fourth Proportional to 647.12, 892.96 and 398.40

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Solution

The fourth proportional to 647.12, 892.96 and 398.40 is: 549.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    647.12 : 892.96 = 398.40 : x
  2. Step 2: Convert to fraction form
    647.12/892.96 = 398.40/x
  3. Step 3: Cross multiply
    647.12x = 892.96 × 398.40
  4. Step 4: Simplify right side
    647.12x = 355,755.26
  5. Step 5: Solve for x
    x = 355,755.26/647.12
  6. Step 6: Final answer
    x = 549.75

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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.