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Finding the Fourth Proportional to 1,309.91, 1,807.78 and 720.55

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Solution

The fourth proportional to 1,309.91, 1,807.78 and 720.55 is: 994.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,309.91 : 1,807.78 = 720.55 : x
  2. Step 2: Convert to fraction form
    1,309.91/1,807.78 = 720.55/x
  3. Step 3: Cross multiply
    1,309.91x = 1,807.78 × 720.55
  4. Step 4: Simplify right side
    1,309.91x = 1,302,589.56
  5. Step 5: Solve for x
    x = 1,302,589.56/1,309.91
  6. Step 6: Final answer
    x = 994.42

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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.