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Finding the Fourth Proportional to 831.70, 1,247.55 and 791.20

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Solution

The fourth proportional to 831.70, 1,247.55 and 791.20 is: 1,186.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.70 : 1,247.55 = 791.20 : x
  2. Step 2: Convert to fraction form
    831.70/1,247.55 = 791.20/x
  3. Step 3: Cross multiply
    831.70x = 1,247.55 × 791.20
  4. Step 4: Simplify right side
    831.70x = 987,061.56
  5. Step 5: Solve for x
    x = 987,061.56/831.70
  6. Step 6: Final answer
    x = 1,186.80

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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.