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Finding the Fourth Proportional to 687.72, 1,031.70 and 358.80

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Solution

The fourth proportional to 687.72, 1,031.70 and 358.80 is: 538.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.72 : 1,031.70 = 358.80 : x
  2. Step 2: Convert to fraction form
    687.72/1,031.70 = 358.80/x
  3. Step 3: Cross multiply
    687.72x = 1,031.70 × 358.80
  4. Step 4: Simplify right side
    687.72x = 370,171.44
  5. Step 5: Solve for x
    x = 370,171.44/687.72
  6. Step 6: Final answer
    x = 538.26

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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.