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Finding the Fourth Proportional to 969.76, 1,338.47 and 638.21

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Solution

The fourth proportional to 969.76, 1,338.47 and 638.21 is: 880.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    969.76 : 1,338.47 = 638.21 : x
  2. Step 2: Convert to fraction form
    969.76/1,338.47 = 638.21/x
  3. Step 3: Cross multiply
    969.76x = 1,338.47 × 638.21
  4. Step 4: Simplify right side
    969.76x = 854,229.88
  5. Step 5: Solve for x
    x = 854,229.88/969.76
  6. Step 6: Final answer
    x = 880.87

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.