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Finding the Fourth Proportional to 1,331.12, 1,993.90 and 781.64

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Solution

The fourth proportional to 1,331.12, 1,993.90 and 781.64 is: 1,170.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,331.12 : 1,993.90 = 781.64 : x
  2. Step 2: Convert to fraction form
    1,331.12/1,993.90 = 781.64/x
  3. Step 3: Cross multiply
    1,331.12x = 1,993.90 × 781.64
  4. Step 4: Simplify right side
    1,331.12x = 1,558,512.00
  5. Step 5: Solve for x
    x = 1,558,512.00/1,331.12
  6. Step 6: Final answer
    x = 1,170.83

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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.