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Finding the Fourth Proportional to 809.78, 1,215.57 and 323.16

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Solution

The fourth proportional to 809.78, 1,215.57 and 323.16 is: 485.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.78 : 1,215.57 = 323.16 : x
  2. Step 2: Convert to fraction form
    809.78/1,215.57 = 323.16/x
  3. Step 3: Cross multiply
    809.78x = 1,215.57 × 323.16
  4. Step 4: Simplify right side
    809.78x = 392,823.60
  5. Step 5: Solve for x
    x = 392,823.60/809.78
  6. Step 6: Final answer
    x = 485.10

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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.