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Finding the Fourth Proportional to 831.78, 1,248.18 and 485.28

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Solution

The fourth proportional to 831.78, 1,248.18 and 485.28 is: 728.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.78 : 1,248.18 = 485.28 : x
  2. Step 2: Convert to fraction form
    831.78/1,248.18 = 485.28/x
  3. Step 3: Cross multiply
    831.78x = 1,248.18 × 485.28
  4. Step 4: Simplify right side
    831.78x = 605,716.79
  5. Step 5: Solve for x
    x = 605,716.79/831.78
  6. Step 6: Final answer
    x = 728.22

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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.