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Finding the Fourth Proportional to 1,249.78, 1,874.95 and 428.05

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Solution

The fourth proportional to 1,249.78, 1,874.95 and 428.05 is: 642.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,249.78 : 1,874.95 = 428.05 : x
  2. Step 2: Convert to fraction form
    1,249.78/1,874.95 = 428.05/x
  3. Step 3: Cross multiply
    1,249.78x = 1,874.95 × 428.05
  4. Step 4: Simplify right side
    1,249.78x = 802,568.73
  5. Step 5: Solve for x
    x = 802,568.73/1,249.78
  6. Step 6: Final answer
    x = 642.17

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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.