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Finding the Fourth Proportional to 831.40, 1,247.20 and 398.25

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Solution

The fourth proportional to 831.40, 1,247.20 and 398.25 is: 597.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.40 : 1,247.20 = 398.25 : x
  2. Step 2: Convert to fraction form
    831.40/1,247.20 = 398.25/x
  3. Step 3: Cross multiply
    831.40x = 1,247.20 × 398.25
  4. Step 4: Simplify right side
    831.40x = 496,696.40
  5. Step 5: Solve for x
    x = 496,696.40/831.40
  6. Step 6: Final answer
    x = 597.42

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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.