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Finding the Fourth Proportional to 857.57, 1,285.66 and 789.21

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Solution

The fourth proportional to 857.57, 1,285.66 and 789.21 is: 1,183.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.57 : 1,285.66 = 789.21 : x
  2. Step 2: Convert to fraction form
    857.57/1,285.66 = 789.21/x
  3. Step 3: Cross multiply
    857.57x = 1,285.66 × 789.21
  4. Step 4: Simplify right side
    857.57x = 1,014,653.76
  5. Step 5: Solve for x
    x = 1,014,653.76/857.57
  6. Step 6: Final answer
    x = 1,183.18

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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.