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Finding the Fourth Proportional to 685.86, 1,028.10 and 320.40

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Solution

The fourth proportional to 685.86, 1,028.10 and 320.40 is: 480.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.86 : 1,028.10 = 320.40 : x
  2. Step 2: Convert to fraction form
    685.86/1,028.10 = 320.40/x
  3. Step 3: Cross multiply
    685.86x = 1,028.10 × 320.40
  4. Step 4: Simplify right side
    685.86x = 329,403.24
  5. Step 5: Solve for x
    x = 329,403.24/685.86
  6. Step 6: Final answer
    x = 480.28

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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.