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Finding the Fourth Proportional to 1,221.21, 1,685.57 and 697.55

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Solution

The fourth proportional to 1,221.21, 1,685.57 and 697.55 is: 962.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.21 : 1,685.57 = 697.55 : x
  2. Step 2: Convert to fraction form
    1,221.21/1,685.57 = 697.55/x
  3. Step 3: Cross multiply
    1,221.21x = 1,685.57 × 697.55
  4. Step 4: Simplify right side
    1,221.21x = 1,175,757.44
  5. Step 5: Solve for x
    x = 1,175,757.44/1,221.21
  6. Step 6: Final answer
    x = 962.78

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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.