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Finding the Fourth Proportional to 687.76, 951.35 and 643.68

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Solution

The fourth proportional to 687.76, 951.35 and 643.68 is: 890.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.76 : 951.35 = 643.68 : x
  2. Step 2: Convert to fraction form
    687.76/951.35 = 643.68/x
  3. Step 3: Cross multiply
    687.76x = 951.35 × 643.68
  4. Step 4: Simplify right side
    687.76x = 612,361.75
  5. Step 5: Solve for x
    x = 612,361.75/687.76
  6. Step 6: Final answer
    x = 890.37

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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.