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Finding the Fourth Proportional to 872.75, 1,309.89 and 780.05

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Solution

The fourth proportional to 872.75, 1,309.89 and 780.05 is: 1,170.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    872.75 : 1,309.89 = 780.05 : x
  2. Step 2: Convert to fraction form
    872.75/1,309.89 = 780.05/x
  3. Step 3: Cross multiply
    872.75x = 1,309.89 × 780.05
  4. Step 4: Simplify right side
    872.75x = 1,021,773.15
  5. Step 5: Solve for x
    x = 1,021,773.15/872.75
  6. Step 6: Final answer
    x = 1,170.76

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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.