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Finding the Fourth Proportional to 831.20, 1,246.80 and 776.80

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Solution

The fourth proportional to 831.20, 1,246.80 and 776.80 is: 1,165.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.20 : 1,246.80 = 776.80 : x
  2. Step 2: Convert to fraction form
    831.20/1,246.80 = 776.80/x
  3. Step 3: Cross multiply
    831.20x = 1,246.80 × 776.80
  4. Step 4: Simplify right side
    831.20x = 968,514.24
  5. Step 5: Solve for x
    x = 968,514.24/831.20
  6. Step 6: Final answer
    x = 1,165.20

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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.