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Finding the Fourth Proportional to 862.56, 1,290.67 and 815.65

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Solution

The fourth proportional to 862.56, 1,290.67 and 815.65 is: 1,220.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    862.56 : 1,290.67 = 815.65 : x
  2. Step 2: Convert to fraction form
    862.56/1,290.67 = 815.65/x
  3. Step 3: Cross multiply
    862.56x = 1,290.67 × 815.65
  4. Step 4: Simplify right side
    862.56x = 1,052,729.72
  5. Step 5: Solve for x
    x = 1,052,729.72/862.56
  6. Step 6: Final answer
    x = 1,220.47

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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.