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Finding the Fourth Proportional to 1,309.61, 1,805.90 and 911.72

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Solution

The fourth proportional to 1,309.61, 1,805.90 and 911.72 is: 1,257.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,309.61 : 1,805.90 = 911.72 : x
  2. Step 2: Convert to fraction form
    1,309.61/1,805.90 = 911.72/x
  3. Step 3: Cross multiply
    1,309.61x = 1,805.90 × 911.72
  4. Step 4: Simplify right side
    1,309.61x = 1,646,461.56
  5. Step 5: Solve for x
    x = 1,646,461.56/1,309.61
  6. Step 6: Final answer
    x = 1,257.22

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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.