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Finding the Fourth Proportional to 856.80, 1,285.74 and 613.80

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Solution

The fourth proportional to 856.80, 1,285.74 and 613.80 is: 921.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.80 : 1,285.74 = 613.80 : x
  2. Step 2: Convert to fraction form
    856.80/1,285.74 = 613.80/x
  3. Step 3: Cross multiply
    856.80x = 1,285.74 × 613.80
  4. Step 4: Simplify right side
    856.80x = 789,187.21
  5. Step 5: Solve for x
    x = 789,187.21/856.80
  6. Step 6: Final answer
    x = 921.09

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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.