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Finding the Fourth Proportional to 831.34, 1,247.31 and 392.72

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Solution

The fourth proportional to 831.34, 1,247.31 and 392.72 is: 589.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.34 : 1,247.31 = 392.72 : x
  2. Step 2: Convert to fraction form
    831.34/1,247.31 = 392.72/x
  3. Step 3: Cross multiply
    831.34x = 1,247.31 × 392.72
  4. Step 4: Simplify right side
    831.34x = 489,841.62
  5. Step 5: Solve for x
    x = 489,841.62/831.34
  6. Step 6: Final answer
    x = 589.22

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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.