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Finding the Fourth Proportional to 857.65, 1,286.67 and 280.39

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Solution

The fourth proportional to 857.65, 1,286.67 and 280.39 is: 420.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.65 : 1,286.67 = 280.39 : x
  2. Step 2: Convert to fraction form
    857.65/1,286.67 = 280.39/x
  3. Step 3: Cross multiply
    857.65x = 1,286.67 × 280.39
  4. Step 4: Simplify right side
    857.65x = 360,769.40
  5. Step 5: Solve for x
    x = 360,769.40/857.65
  6. Step 6: Final answer
    x = 420.65

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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.