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Finding the Fourth Proportional to 939.90, 1,296.66 and 644.65

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Solution

The fourth proportional to 939.90, 1,296.66 and 644.65 is: 889.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.90 : 1,296.66 = 644.65 : x
  2. Step 2: Convert to fraction form
    939.90/1,296.66 = 644.65/x
  3. Step 3: Cross multiply
    939.90x = 1,296.66 × 644.65
  4. Step 4: Simplify right side
    939.90x = 835,891.87
  5. Step 5: Solve for x
    x = 835,891.87/939.90
  6. Step 6: Final answer
    x = 889.34

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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.