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Finding the Fourth Proportional to 687.35, 1,031.26 and 378.81

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Solution

The fourth proportional to 687.35, 1,031.26 and 378.81 is: 568.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.35 : 1,031.26 = 378.81 : x
  2. Step 2: Convert to fraction form
    687.35/1,031.26 = 378.81/x
  3. Step 3: Cross multiply
    687.35x = 1,031.26 × 378.81
  4. Step 4: Simplify right side
    687.35x = 390,651.60
  5. Step 5: Solve for x
    x = 390,651.60/687.35
  6. Step 6: Final answer
    x = 568.34

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.