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Finding the Fourth Proportional to 642.70, 887 and 393.96

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Solution

The fourth proportional to 642.70, 887 and 393.96 is: 543.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.70 : 887 = 393.96 : x
  2. Step 2: Convert to fraction form
    642.70/887 = 393.96/x
  3. Step 3: Cross multiply
    642.70x = 887 × 393.96
  4. Step 4: Simplify right side
    642.70x = 349,442.52
  5. Step 5: Solve for x
    x = 349,442.52/642.70
  6. Step 6: Final answer
    x = 543.71

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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.