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Finding the Fourth Proportional to 1,188.78, 1,640.52 and 691.37

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Solution

The fourth proportional to 1,188.78, 1,640.52 and 691.37 is: 954.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,188.78 : 1,640.52 = 691.37 : x
  2. Step 2: Convert to fraction form
    1,188.78/1,640.52 = 691.37/x
  3. Step 3: Cross multiply
    1,188.78x = 1,640.52 × 691.37
  4. Step 4: Simplify right side
    1,188.78x = 1,134,204.26
  5. Step 5: Solve for x
    x = 1,134,204.26/1,188.78
  6. Step 6: Final answer
    x = 954.09

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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.