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Finding the Fourth Proportional to 1,279.80, 1,918.95 and 402.09

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Solution

The fourth proportional to 1,279.80, 1,918.95 and 402.09 is: 602.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,279.80 : 1,918.95 = 402.09 : x
  2. Step 2: Convert to fraction form
    1,279.80/1,918.95 = 402.09/x
  3. Step 3: Cross multiply
    1,279.80x = 1,918.95 × 402.09
  4. Step 4: Simplify right side
    1,279.80x = 771,590.61
  5. Step 5: Solve for x
    x = 771,590.61/1,279.80
  6. Step 6: Final answer
    x = 602.90

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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.