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Finding the Third Proportional to 421.77 and 831.20

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Solution

The third proportional to 421.77 and 831.20 is: 1,638.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.77 : 831.20 = 831.20 : x
  2. Step 2: Convert to fraction form
    421.77/831.20 = 831.20/x
  3. Step 3: Cross multiply
    421.77x = 831.20 × 831.20
  4. Step 4: Simplify right side
    421.77x = 690,892.14
  5. Step 5: Solve for x
    x = 690,892.14/421.77
  6. Step 6: Final answer
    x = 1,638.08

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Why These Related Problems?

These problems maintain the same ratio (1.97) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.