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Finding the Fourth Proportional to 687.49, 1,030.31 and 321.49

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Solution

The fourth proportional to 687.49, 1,030.31 and 321.49 is: 481.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.49 : 1,030.31 = 321.49 : x
  2. Step 2: Convert to fraction form
    687.49/1,030.31 = 321.49/x
  3. Step 3: Cross multiply
    687.49x = 1,030.31 × 321.49
  4. Step 4: Simplify right side
    687.49x = 331,227.60
  5. Step 5: Solve for x
    x = 331,227.60/687.49
  6. Step 6: Final answer
    x = 481.80

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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.