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Finding the Fourth Proportional to 857.80, 1,286.70 and 665.56

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Solution

The fourth proportional to 857.80, 1,286.70 and 665.56 is: 998.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.80 : 1,286.70 = 665.56 : x
  2. Step 2: Convert to fraction form
    857.80/1,286.70 = 665.56/x
  3. Step 3: Cross multiply
    857.80x = 1,286.70 × 665.56
  4. Step 4: Simplify right side
    857.80x = 856,376.05
  5. Step 5: Solve for x
    x = 856,376.05/857.80
  6. Step 6: Final answer
    x = 998.34

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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.