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Finding the Fourth Proportional to 831.26, 1,247.67 and 420.69

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Solution

The fourth proportional to 831.26, 1,247.67 and 420.69 is: 631.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.26 : 1,247.67 = 420.69 : x
  2. Step 2: Convert to fraction form
    831.26/1,247.67 = 420.69/x
  3. Step 3: Cross multiply
    831.26x = 1,247.67 × 420.69
  4. Step 4: Simplify right side
    831.26x = 524,882.29
  5. Step 5: Solve for x
    x = 524,882.29/831.26
  6. Step 6: Final answer
    x = 631.43

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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.