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Finding the Fourth Proportional to 809.90, 1,212.45 and 485.90

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Solution

The fourth proportional to 809.90, 1,212.45 and 485.90 is: 727.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.90 : 1,212.45 = 485.90 : x
  2. Step 2: Convert to fraction form
    809.90/1,212.45 = 485.90/x
  3. Step 3: Cross multiply
    809.90x = 1,212.45 × 485.90
  4. Step 4: Simplify right side
    809.90x = 589,129.46
  5. Step 5: Solve for x
    x = 589,129.46/809.90
  6. Step 6: Final answer
    x = 727.41

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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.