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Finding the Fourth Proportional to 1,028.79, 1,420.31 and 680.09

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Solution

The fourth proportional to 1,028.79, 1,420.31 and 680.09 is: 938.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,028.79 : 1,420.31 = 680.09 : x
  2. Step 2: Convert to fraction form
    1,028.79/1,420.31 = 680.09/x
  3. Step 3: Cross multiply
    1,028.79x = 1,420.31 × 680.09
  4. Step 4: Simplify right side
    1,028.79x = 965,928.13
  5. Step 5: Solve for x
    x = 965,928.13/1,028.79
  6. Step 6: Final answer
    x = 938.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.