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Finding the Fourth Proportional to 831.31, 1,247.33 and 420.72

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Solution

The fourth proportional to 831.31, 1,247.33 and 420.72 is: 631.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.31 : 1,247.33 = 420.72 : x
  2. Step 2: Convert to fraction form
    831.31/1,247.33 = 420.72/x
  3. Step 3: Cross multiply
    831.31x = 1,247.33 × 420.72
  4. Step 4: Simplify right side
    831.31x = 524,774.57
  5. Step 5: Solve for x
    x = 524,774.57/831.31
  6. Step 6: Final answer
    x = 631.26

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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.