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Finding the Fourth Proportional to 642.69, 886.71 and 393.88

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Solution

The fourth proportional to 642.69, 886.71 and 393.88 is: 543.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.69 : 886.71 = 393.88 : x
  2. Step 2: Convert to fraction form
    642.69/886.71 = 393.88/x
  3. Step 3: Cross multiply
    642.69x = 886.71 × 393.88
  4. Step 4: Simplify right side
    642.69x = 349,257.33
  5. Step 5: Solve for x
    x = 349,257.33/642.69
  6. Step 6: Final answer
    x = 543.43

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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.