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Finding the Fourth Proportional to 1,279.49, 1,916.09 and 815.90

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Solution

The fourth proportional to 1,279.49, 1,916.09 and 815.90 is: 1,221.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,279.49 : 1,916.09 = 815.90 : x
  2. Step 2: Convert to fraction form
    1,279.49/1,916.09 = 815.90/x
  3. Step 3: Cross multiply
    1,279.49x = 1,916.09 × 815.90
  4. Step 4: Simplify right side
    1,279.49x = 1,563,333.75
  5. Step 5: Solve for x
    x = 1,563,333.75/1,279.49
  6. Step 6: Final answer
    x = 1,221.84

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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.