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Finding the Fourth Proportional to 643.18, 887.79 and 407.20

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Solution

The fourth proportional to 643.18, 887.79 and 407.20 is: 562.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.18 : 887.79 = 407.20 : x
  2. Step 2: Convert to fraction form
    643.18/887.79 = 407.20/x
  3. Step 3: Cross multiply
    643.18x = 887.79 × 407.20
  4. Step 4: Simplify right side
    643.18x = 361,508.09
  5. Step 5: Solve for x
    x = 361,508.09/643.18
  6. Step 6: Final answer
    x = 562.06

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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.