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Finding the Fourth Proportional to 812.18, 1,120.42 and 780.75

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Solution

The fourth proportional to 812.18, 1,120.42 and 780.75 is: 1,077.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.18 : 1,120.42 = 780.75 : x
  2. Step 2: Convert to fraction form
    812.18/1,120.42 = 780.75/x
  3. Step 3: Cross multiply
    812.18x = 1,120.42 × 780.75
  4. Step 4: Simplify right side
    812.18x = 874,767.92
  5. Step 5: Solve for x
    x = 874,767.92/812.18
  6. Step 6: Final answer
    x = 1,077.06

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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.