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Finding the Fourth Proportional to 861.09, 1,290.85 and 313.15

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Solution

The fourth proportional to 861.09, 1,290.85 and 313.15 is: 469.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.09 : 1,290.85 = 313.15 : x
  2. Step 2: Convert to fraction form
    861.09/1,290.85 = 313.15/x
  3. Step 3: Cross multiply
    861.09x = 1,290.85 × 313.15
  4. Step 4: Simplify right side
    861.09x = 404,229.68
  5. Step 5: Solve for x
    x = 404,229.68/861.09
  6. Step 6: Final answer
    x = 469.44

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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.