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Finding the Fourth Proportional to 831.45, 1,247.63 and 311.81

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Solution

The fourth proportional to 831.45, 1,247.63 and 311.81 is: 467.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.45 : 1,247.63 = 311.81 : x
  2. Step 2: Convert to fraction form
    831.45/1,247.63 = 311.81/x
  3. Step 3: Cross multiply
    831.45x = 1,247.63 × 311.81
  4. Step 4: Simplify right side
    831.45x = 389,015.71
  5. Step 5: Solve for x
    x = 389,015.71/831.45
  6. Step 6: Final answer
    x = 467.88

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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.