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Finding the Fourth Proportional to 1,209.81, 1,813.23 and 861.25

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Solution

The fourth proportional to 1,209.81, 1,813.23 and 861.25 is: 1,290.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.81 : 1,813.23 = 861.25 : x
  2. Step 2: Convert to fraction form
    1,209.81/1,813.23 = 861.25/x
  3. Step 3: Cross multiply
    1,209.81x = 1,813.23 × 861.25
  4. Step 4: Simplify right side
    1,209.81x = 1,561,640.03
  5. Step 5: Solve for x
    x = 1,561,640.03/1,209.81
  6. Step 6: Final answer
    x = 1,290.82

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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.