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Finding the Fourth Proportional to 1,279.70, 1,918.72 and 840.43

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Solution

The fourth proportional to 1,279.70, 1,918.72 and 840.43 is: 1,260.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,279.70 : 1,918.72 = 840.43 : x
  2. Step 2: Convert to fraction form
    1,279.70/1,918.72 = 840.43/x
  3. Step 3: Cross multiply
    1,279.70x = 1,918.72 × 840.43
  4. Step 4: Simplify right side
    1,279.70x = 1,612,549.85
  5. Step 5: Solve for x
    x = 1,612,549.85/1,279.70
  6. Step 6: Final answer
    x = 1,260.10

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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.