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Finding the Fourth Proportional to 1,205.53, 1,665 and 811.87

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Solution

The fourth proportional to 1,205.53, 1,665 and 811.87 is: 1,121.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,205.53 : 1,665 = 811.87 : x
  2. Step 2: Convert to fraction form
    1,205.53/1,665 = 811.87/x
  3. Step 3: Cross multiply
    1,205.53x = 1,665 × 811.87
  4. Step 4: Simplify right side
    1,205.53x = 1,351,765.63
  5. Step 5: Solve for x
    x = 1,351,765.63/1,205.53
  6. Step 6: Final answer
    x = 1,121.30

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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.