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Finding the Fourth Proportional to 831.79, 1,247.85 and 318.75

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Solution

The fourth proportional to 831.79, 1,247.85 and 318.75 is: 478.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.79 : 1,247.85 = 318.75 : x
  2. Step 2: Convert to fraction form
    831.79/1,247.85 = 318.75/x
  3. Step 3: Cross multiply
    831.79x = 1,247.85 × 318.75
  4. Step 4: Simplify right side
    831.79x = 397,750.59
  5. Step 5: Solve for x
    x = 397,750.59/831.79
  6. Step 6: Final answer
    x = 478.19

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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.