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Finding the Fourth Proportional to 1,392.40, 2,089.14 and 418.78

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Solution

The fourth proportional to 1,392.40, 2,089.14 and 418.78 is: 628.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,392.40 : 2,089.14 = 418.78 : x
  2. Step 2: Convert to fraction form
    1,392.40/2,089.14 = 418.78/x
  3. Step 3: Cross multiply
    1,392.40x = 2,089.14 × 418.78
  4. Step 4: Simplify right side
    1,392.40x = 874,890.05
  5. Step 5: Solve for x
    x = 874,890.05/1,392.40
  6. Step 6: Final answer
    x = 628.33

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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.