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Finding the Fourth Proportional to 815.28, 1,222.88 and 321.72

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Solution

The fourth proportional to 815.28, 1,222.88 and 321.72 is: 482.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.28 : 1,222.88 = 321.72 : x
  2. Step 2: Convert to fraction form
    815.28/1,222.88 = 321.72/x
  3. Step 3: Cross multiply
    815.28x = 1,222.88 × 321.72
  4. Step 4: Simplify right side
    815.28x = 393,424.95
  5. Step 5: Solve for x
    x = 393,424.95/815.28
  6. Step 6: Final answer
    x = 482.56

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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.