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Finding the Fourth Proportional to 685.76, 1,028.65 and 172.76

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Solution

The fourth proportional to 685.76, 1,028.65 and 172.76 is: 259.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.76 : 1,028.65 = 172.76 : x
  2. Step 2: Convert to fraction form
    685.76/1,028.65 = 172.76/x
  3. Step 3: Cross multiply
    685.76x = 1,028.65 × 172.76
  4. Step 4: Simplify right side
    685.76x = 177,709.57
  5. Step 5: Solve for x
    x = 177,709.57/685.76
  6. Step 6: Final answer
    x = 259.14

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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.