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Finding the Fourth Proportional to 836.80, 1,255.20 and 642.40

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Solution

The fourth proportional to 836.80, 1,255.20 and 642.40 is: 963.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    836.80 : 1,255.20 = 642.40 : x
  2. Step 2: Convert to fraction form
    836.80/1,255.20 = 642.40/x
  3. Step 3: Cross multiply
    836.80x = 1,255.20 × 642.40
  4. Step 4: Simplify right side
    836.80x = 806,340.48
  5. Step 5: Solve for x
    x = 806,340.48/836.80
  6. Step 6: Final answer
    x = 963.60

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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.