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Finding the Fourth Proportional to 641.79, 885.63 and 405.78

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Solution

The fourth proportional to 641.79, 885.63 and 405.78 is: 559.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.79 : 885.63 = 405.78 : x
  2. Step 2: Convert to fraction form
    641.79/885.63 = 405.78/x
  3. Step 3: Cross multiply
    641.79x = 885.63 × 405.78
  4. Step 4: Simplify right side
    641.79x = 359,370.94
  5. Step 5: Solve for x
    x = 359,370.94/641.79
  6. Step 6: Final answer
    x = 559.95

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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.