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Finding the Fourth Proportional to 1,391.23, 2,086.80 and 661.33

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Solution

The fourth proportional to 1,391.23, 2,086.80 and 661.33 is: 991.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.23 : 2,086.80 = 661.33 : x
  2. Step 2: Convert to fraction form
    1,391.23/2,086.80 = 661.33/x
  3. Step 3: Cross multiply
    1,391.23x = 2,086.80 × 661.33
  4. Step 4: Simplify right side
    1,391.23x = 1,380,063.44
  5. Step 5: Solve for x
    x = 1,380,063.44/1,391.23
  6. Step 6: Final answer
    x = 991.97

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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.