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Finding the Fourth Proportional to 687.76, 1,031.20 and 340.68

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Solution

The fourth proportional to 687.76, 1,031.20 and 340.68 is: 510.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.76 : 1,031.20 = 340.68 : x
  2. Step 2: Convert to fraction form
    687.76/1,031.20 = 340.68/x
  3. Step 3: Cross multiply
    687.76x = 1,031.20 × 340.68
  4. Step 4: Simplify right side
    687.76x = 351,309.22
  5. Step 5: Solve for x
    x = 351,309.22/687.76
  6. Step 6: Final answer
    x = 510.80

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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.