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Finding the Fourth Proportional to 821.44, 1,231.20 and 638.28

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Solution

The fourth proportional to 821.44, 1,231.20 and 638.28 is: 956.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.44 : 1,231.20 = 638.28 : x
  2. Step 2: Convert to fraction form
    821.44/1,231.20 = 638.28/x
  3. Step 3: Cross multiply
    821.44x = 1,231.20 × 638.28
  4. Step 4: Simplify right side
    821.44x = 785,850.34
  5. Step 5: Solve for x
    x = 785,850.34/821.44
  6. Step 6: Final answer
    x = 956.67

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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.