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Finding the Fourth Proportional to 1,188.72, 1,640.49 and 664.71

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Solution

The fourth proportional to 1,188.72, 1,640.49 and 664.71 is: 917.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,188.72 : 1,640.49 = 664.71 : x
  2. Step 2: Convert to fraction form
    1,188.72/1,640.49 = 664.71/x
  3. Step 3: Cross multiply
    1,188.72x = 1,640.49 × 664.71
  4. Step 4: Simplify right side
    1,188.72x = 1,090,450.11
  5. Step 5: Solve for x
    x = 1,090,450.11/1,188.72
  6. Step 6: Final answer
    x = 917.33

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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.