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Finding the Fourth Proportional to 1,331.88, 1,991.25 and 1,128.72

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Solution

The fourth proportional to 1,331.88, 1,991.25 and 1,128.72 is: 1,687.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,331.88 : 1,991.25 = 1,128.72 : x
  2. Step 2: Convert to fraction form
    1,331.88/1,991.25 = 1,128.72/x
  3. Step 3: Cross multiply
    1,331.88x = 1,991.25 × 1,128.72
  4. Step 4: Simplify right side
    1,331.88x = 2,247,563.70
  5. Step 5: Solve for x
    x = 2,247,563.70/1,331.88
  6. Step 6: Final answer
    x = 1,687.51

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.