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Finding the Fourth Proportional to 1,311.05, 1,970.28 and 990.29

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Solution

The fourth proportional to 1,311.05, 1,970.28 and 990.29 is: 1,488.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.05 : 1,970.28 = 990.29 : x
  2. Step 2: Convert to fraction form
    1,311.05/1,970.28 = 990.29/x
  3. Step 3: Cross multiply
    1,311.05x = 1,970.28 × 990.29
  4. Step 4: Simplify right side
    1,311.05x = 1,951,138.73
  5. Step 5: Solve for x
    x = 1,951,138.73/1,311.05
  6. Step 6: Final answer
    x = 1,488.23

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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.