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Finding the Fourth Proportional to 831.60, 1,247.04 and 639.36

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Solution

The fourth proportional to 831.60, 1,247.04 and 639.36 is: 958.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.60 : 1,247.04 = 639.36 : x
  2. Step 2: Convert to fraction form
    831.60/1,247.04 = 639.36/x
  3. Step 3: Cross multiply
    831.60x = 1,247.04 × 639.36
  4. Step 4: Simplify right side
    831.60x = 797,307.49
  5. Step 5: Solve for x
    x = 797,307.49/831.60
  6. Step 6: Final answer
    x = 958.76

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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.