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Finding the Fourth Proportional to 485.80, 725.36 and 421

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Solution

The fourth proportional to 485.80, 725.36 and 421 is: 628.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.80 : 725.36 = 421 : x
  2. Step 2: Convert to fraction form
    485.80/725.36 = 421/x
  3. Step 3: Cross multiply
    485.80x = 725.36 × 421
  4. Step 4: Simplify right side
    485.80x = 305,376.56
  5. Step 5: Solve for x
    x = 305,376.56/485.80
  6. Step 6: Final answer
    x = 628.61

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.