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Finding the Fourth Proportional to 1,211.45, 1,672.10 and 687.78

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Solution

The fourth proportional to 1,211.45, 1,672.10 and 687.78 is: 949.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.45 : 1,672.10 = 687.78 : x
  2. Step 2: Convert to fraction form
    1,211.45/1,672.10 = 687.78/x
  3. Step 3: Cross multiply
    1,211.45x = 1,672.10 × 687.78
  4. Step 4: Simplify right side
    1,211.45x = 1,150,033.50
  5. Step 5: Solve for x
    x = 1,150,033.50/1,211.45
  6. Step 6: Final answer
    x = 949.31

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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.