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Finding the Fourth Proportional to 1,221.48, 1,685.21 and 697.21

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Solution

The fourth proportional to 1,221.48, 1,685.21 and 697.21 is: 961.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.48 : 1,685.21 = 697.21 : x
  2. Step 2: Convert to fraction form
    1,221.48/1,685.21 = 697.21/x
  3. Step 3: Cross multiply
    1,221.48x = 1,685.21 × 697.21
  4. Step 4: Simplify right side
    1,221.48x = 1,174,937.57
  5. Step 5: Solve for x
    x = 1,174,937.57/1,221.48
  6. Step 6: Final answer
    x = 961.90

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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.