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Finding the Fourth Proportional to 861.20, 1,290.20 and 803.60

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Solution

The fourth proportional to 861.20, 1,290.20 and 803.60 is: 1,203.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.20 : 1,290.20 = 803.60 : x
  2. Step 2: Convert to fraction form
    861.20/1,290.20 = 803.60/x
  3. Step 3: Cross multiply
    861.20x = 1,290.20 × 803.60
  4. Step 4: Simplify right side
    861.20x = 1,036,804.72
  5. Step 5: Solve for x
    x = 1,036,804.72/861.20
  6. Step 6: Final answer
    x = 1,203.91

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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.