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Finding the Fourth Proportional to 1,311.18, 1,809.46 and 721.76

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Solution

The fourth proportional to 1,311.18, 1,809.46 and 721.76 is: 996.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.18 : 1,809.46 = 721.76 : x
  2. Step 2: Convert to fraction form
    1,311.18/1,809.46 = 721.76/x
  3. Step 3: Cross multiply
    1,311.18x = 1,809.46 × 721.76
  4. Step 4: Simplify right side
    1,311.18x = 1,305,995.85
  5. Step 5: Solve for x
    x = 1,305,995.85/1,311.18
  6. Step 6: Final answer
    x = 996.05

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1.5x scale

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.