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Finding the Fourth Proportional to 685.12, 1,028.40 and 252.40

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Solution

The fourth proportional to 685.12, 1,028.40 and 252.40 is: 378.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.12 : 1,028.40 = 252.40 : x
  2. Step 2: Convert to fraction form
    685.12/1,028.40 = 252.40/x
  3. Step 3: Cross multiply
    685.12x = 1,028.40 × 252.40
  4. Step 4: Simplify right side
    685.12x = 259,568.16
  5. Step 5: Solve for x
    x = 259,568.16/685.12
  6. Step 6: Final answer
    x = 378.87

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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.