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Finding the Fourth Proportional to 687.84, 1,031.76 and 399.48

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Solution

The fourth proportional to 687.84, 1,031.76 and 399.48 is: 599.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.84 : 1,031.76 = 399.48 : x
  2. Step 2: Convert to fraction form
    687.84/1,031.76 = 399.48/x
  3. Step 3: Cross multiply
    687.84x = 1,031.76 × 399.48
  4. Step 4: Simplify right side
    687.84x = 412,167.48
  5. Step 5: Solve for x
    x = 412,167.48/687.84
  6. Step 6: Final answer
    x = 599.22

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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.