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Finding the Fourth Proportional to 1,011.60, 1,396.80 and 680.40

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Solution

The fourth proportional to 1,011.60, 1,396.80 and 680.40 is: 939.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,011.60 : 1,396.80 = 680.40 : x
  2. Step 2: Convert to fraction form
    1,011.60/1,396.80 = 680.40/x
  3. Step 3: Cross multiply
    1,011.60x = 1,396.80 × 680.40
  4. Step 4: Simplify right side
    1,011.60x = 950,382.72
  5. Step 5: Solve for x
    x = 950,382.72/1,011.60
  6. Step 6: Final answer
    x = 939.48

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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.