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Finding the Fourth Proportional to 812.22, 1,211.21 and 780.72

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Solution

The fourth proportional to 812.22, 1,211.21 and 780.72 is: 1,164.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.22 : 1,211.21 = 780.72 : x
  2. Step 2: Convert to fraction form
    812.22/1,211.21 = 780.72/x
  3. Step 3: Cross multiply
    812.22x = 1,211.21 × 780.72
  4. Step 4: Simplify right side
    812.22x = 945,611.97
  5. Step 5: Solve for x
    x = 945,611.97/812.22
  6. Step 6: Final answer
    x = 1,164.23

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.