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Finding the Fourth Proportional to 969.78, 1,338.75 and 638.46

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Solution

The fourth proportional to 969.78, 1,338.75 and 638.46 is: 881.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    969.78 : 1,338.75 = 638.46 : x
  2. Step 2: Convert to fraction form
    969.78/1,338.75 = 638.46/x
  3. Step 3: Cross multiply
    969.78x = 1,338.75 × 638.46
  4. Step 4: Simplify right side
    969.78x = 854,738.33
  5. Step 5: Solve for x
    x = 854,738.33/969.78
  6. Step 6: Final answer
    x = 881.37

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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.