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Finding the Fourth Proportional to 1,292.90, 1,939.41 and 427.21

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Solution

The fourth proportional to 1,292.90, 1,939.41 and 427.21 is: 640.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,292.90 : 1,939.41 = 427.21 : x
  2. Step 2: Convert to fraction form
    1,292.90/1,939.41 = 427.21/x
  3. Step 3: Cross multiply
    1,292.90x = 1,939.41 × 427.21
  4. Step 4: Simplify right side
    1,292.90x = 828,530.50
  5. Step 5: Solve for x
    x = 828,530.50/1,292.90
  6. Step 6: Final answer
    x = 640.83

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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.