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Finding the Fourth Proportional to 485.78, 670.26 and 308.78

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Solution

The fourth proportional to 485.78, 670.26 and 308.78 is: 426.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.78 : 670.26 = 308.78 : x
  2. Step 2: Convert to fraction form
    485.78/670.26 = 308.78/x
  3. Step 3: Cross multiply
    485.78x = 670.26 × 308.78
  4. Step 4: Simplify right side
    485.78x = 206,962.88
  5. Step 5: Solve for x
    x = 206,962.88/485.78
  6. Step 6: Final answer
    x = 426.04

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.