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Finding the Fourth Proportional to 642.15, 885.91 and 393.38

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Solution

The fourth proportional to 642.15, 885.91 and 393.38 is: 542.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.15 : 885.91 = 393.38 : x
  2. Step 2: Convert to fraction form
    642.15/885.91 = 393.38/x
  3. Step 3: Cross multiply
    642.15x = 885.91 × 393.38
  4. Step 4: Simplify right side
    642.15x = 348,493.43
  5. Step 5: Solve for x
    x = 348,493.43/642.15
  6. Step 6: Final answer
    x = 542.70

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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.