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Finding the Fourth Proportional to 969.75, 1,338.47 and 638.21

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Solution

The fourth proportional to 969.75, 1,338.47 and 638.21 is: 880.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    969.75 : 1,338.47 = 638.21 : x
  2. Step 2: Convert to fraction form
    969.75/1,338.47 = 638.21/x
  3. Step 3: Cross multiply
    969.75x = 1,338.47 × 638.21
  4. Step 4: Simplify right side
    969.75x = 854,215.06
  5. Step 5: Solve for x
    x = 854,215.06/969.75
  6. Step 6: Final answer
    x = 880.86

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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.