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Finding the Fourth Proportional to 839.90, 1,261.20 and 610.40

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Solution

The fourth proportional to 839.90, 1,261.20 and 610.40 is: 916.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.90 : 1,261.20 = 610.40 : x
  2. Step 2: Convert to fraction form
    839.90/1,261.20 = 610.40/x
  3. Step 3: Cross multiply
    839.90x = 1,261.20 × 610.40
  4. Step 4: Simplify right side
    839.90x = 769,836.48
  5. Step 5: Solve for x
    x = 769,836.48/839.90
  6. Step 6: Final answer
    x = 916.58

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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.