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Finding the Fourth Proportional to 1,221.90, 1,829.61 and 643.56

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Solution

The fourth proportional to 1,221.90, 1,829.61 and 643.56 is: 963.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.90 : 1,829.61 = 643.56 : x
  2. Step 2: Convert to fraction form
    1,221.90/1,829.61 = 643.56/x
  3. Step 3: Cross multiply
    1,221.90x = 1,829.61 × 643.56
  4. Step 4: Simplify right side
    1,221.90x = 1,177,463.81
  5. Step 5: Solve for x
    x = 1,177,463.81/1,221.90
  6. Step 6: Final answer
    x = 963.63

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.