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Finding the Fourth Proportional to 861.99, 1,189.67 and 809.21

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Solution

The fourth proportional to 861.99, 1,189.67 and 809.21 is: 1,116.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.99 : 1,189.67 = 809.21 : x
  2. Step 2: Convert to fraction form
    861.99/1,189.67 = 809.21/x
  3. Step 3: Cross multiply
    861.99x = 1,189.67 × 809.21
  4. Step 4: Simplify right side
    861.99x = 962,689.65
  5. Step 5: Solve for x
    x = 962,689.65/861.99
  6. Step 6: Final answer
    x = 1,116.82

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.