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Finding the Fourth Proportional to 1,006.87, 1,390.13 and 820.80

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Solution

The fourth proportional to 1,006.87, 1,390.13 and 820.80 is: 1,133.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,006.87 : 1,390.13 = 820.80 : x
  2. Step 2: Convert to fraction form
    1,006.87/1,390.13 = 820.80/x
  3. Step 3: Cross multiply
    1,006.87x = 1,390.13 × 820.80
  4. Step 4: Simplify right side
    1,006.87x = 1,141,018.70
  5. Step 5: Solve for x
    x = 1,141,018.70/1,006.87
  6. Step 6: Final answer
    x = 1,133.23

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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.