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Finding the Fourth Proportional to 685.60, 1,028.09 and 319.88

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Solution

The fourth proportional to 685.60, 1,028.09 and 319.88 is: 479.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.60 : 1,028.09 = 319.88 : x
  2. Step 2: Convert to fraction form
    685.60/1,028.09 = 319.88/x
  3. Step 3: Cross multiply
    685.60x = 1,028.09 × 319.88
  4. Step 4: Simplify right side
    685.60x = 328,868.80
  5. Step 5: Solve for x
    x = 328,868.80/685.60
  6. Step 6: Final answer
    x = 479.68

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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.