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Finding the Fourth Proportional to 642.02, 885.69 and 405.86

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Solution

The fourth proportional to 642.02, 885.69 and 405.86 is: 559.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.02 : 885.69 = 405.86 : x
  2. Step 2: Convert to fraction form
    642.02/885.69 = 405.86/x
  3. Step 3: Cross multiply
    642.02x = 885.69 × 405.86
  4. Step 4: Simplify right side
    642.02x = 359,466.14
  5. Step 5: Solve for x
    x = 359,466.14/642.02
  6. Step 6: Final answer
    x = 559.90

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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.