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Finding the Fourth Proportional to 789.12, 1,087.82 and 505.51

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Solution

The fourth proportional to 789.12, 1,087.82 and 505.51 is: 696.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    789.12 : 1,087.82 = 505.51 : x
  2. Step 2: Convert to fraction form
    789.12/1,087.82 = 505.51/x
  3. Step 3: Cross multiply
    789.12x = 1,087.82 × 505.51
  4. Step 4: Simplify right side
    789.12x = 549,900.54
  5. Step 5: Solve for x
    x = 549,900.54/789.12
  6. Step 6: Final answer
    x = 696.85

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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.