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Finding the Fourth Proportional to 1,188.88, 1,640.72 and 665

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Solution

The fourth proportional to 1,188.88, 1,640.72 and 665 is: 917.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,188.88 : 1,640.72 = 665 : x
  2. Step 2: Convert to fraction form
    1,188.88/1,640.72 = 665/x
  3. Step 3: Cross multiply
    1,188.88x = 1,640.72 × 665
  4. Step 4: Simplify right side
    1,188.88x = 1,091,078.80
  5. Step 5: Solve for x
    x = 1,091,078.80/1,188.88
  6. Step 6: Final answer
    x = 917.74

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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.