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Finding the Fourth Proportional to 685.59, 1,028.39 and 172.59

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Solution

The fourth proportional to 685.59, 1,028.39 and 172.59 is: 258.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.59 : 1,028.39 = 172.59 : x
  2. Step 2: Convert to fraction form
    685.59/1,028.39 = 172.59/x
  3. Step 3: Cross multiply
    685.59x = 1,028.39 × 172.59
  4. Step 4: Simplify right side
    685.59x = 177,488.97
  5. Step 5: Solve for x
    x = 177,488.97/685.59
  6. Step 6: Final answer
    x = 258.89

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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.