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Finding the Fourth Proportional to 431.21, 643.89 and 338.87

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Solution

The fourth proportional to 431.21, 643.89 and 338.87 is: 506.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.21 : 643.89 = 338.87 : x
  2. Step 2: Convert to fraction form
    431.21/643.89 = 338.87/x
  3. Step 3: Cross multiply
    431.21x = 643.89 × 338.87
  4. Step 4: Simplify right side
    431.21x = 218,190.09
  5. Step 5: Solve for x
    x = 218,190.09/431.21
  6. Step 6: Final answer
    x = 506.00

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.