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Finding the Fourth Proportional to 831.28, 1,239.86 and 816.70

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Solution

The fourth proportional to 831.28, 1,239.86 and 816.70 is: 1,218.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.28 : 1,239.86 = 816.70 : x
  2. Step 2: Convert to fraction form
    831.28/1,239.86 = 816.70/x
  3. Step 3: Cross multiply
    831.28x = 1,239.86 × 816.70
  4. Step 4: Simplify right side
    831.28x = 1,012,593.66
  5. Step 5: Solve for x
    x = 1,012,593.66/831.28
  6. Step 6: Final answer
    x = 1,218.11

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.