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Finding the Fourth Proportional to 431.68, 643.37 and 428.11

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Solution

The fourth proportional to 431.68, 643.37 and 428.11 is: 638.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.68 : 643.37 = 428.11 : x
  2. Step 2: Convert to fraction form
    431.68/643.37 = 428.11/x
  3. Step 3: Cross multiply
    431.68x = 643.37 × 428.11
  4. Step 4: Simplify right side
    431.68x = 275,433.13
  5. Step 5: Solve for x
    x = 275,433.13/431.68
  6. Step 6: Final answer
    x = 638.05

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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.