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Finding the Fourth Proportional to 1,287, 1,776.24 and 789.68

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Solution

The fourth proportional to 1,287, 1,776.24 and 789.68 is: 1,089.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287 : 1,776.24 = 789.68 : x
  2. Step 2: Convert to fraction form
    1,287/1,776.24 = 789.68/x
  3. Step 3: Cross multiply
    1,287x = 1,776.24 × 789.68
  4. Step 4: Simplify right side
    1,287x = 1,402,661.20
  5. Step 5: Solve for x
    x = 1,402,661.20/1,287
  6. Step 6: Final answer
    x = 1,089.87

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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.