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Finding the Fourth Proportional to 642.90, 886.78 and 394.12

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Solution

The fourth proportional to 642.90, 886.78 and 394.12 is: 543.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.90 : 886.78 = 394.12 : x
  2. Step 2: Convert to fraction form
    642.90/886.78 = 394.12/x
  3. Step 3: Cross multiply
    642.90x = 886.78 × 394.12
  4. Step 4: Simplify right side
    642.90x = 349,497.73
  5. Step 5: Solve for x
    x = 349,497.73/642.90
  6. Step 6: Final answer
    x = 543.63

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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.