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Finding the Fourth Proportional to 831.40, 1,247.10 and 398.45

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Solution

The fourth proportional to 831.40, 1,247.10 and 398.45 is: 597.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.40 : 1,247.10 = 398.45 : x
  2. Step 2: Convert to fraction form
    831.40/1,247.10 = 398.45/x
  3. Step 3: Cross multiply
    831.40x = 1,247.10 × 398.45
  4. Step 4: Simplify right side
    831.40x = 496,908.62
  5. Step 5: Solve for x
    x = 496,908.62/831.40
  6. Step 6: Final answer
    x = 597.68

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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.