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Finding the Fourth Proportional to 431.21, 643.68 and 399.08

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Solution

The fourth proportional to 431.21, 643.68 and 399.08 is: 595.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.21 : 643.68 = 399.08 : x
  2. Step 2: Convert to fraction form
    431.21/643.68 = 399.08/x
  3. Step 3: Cross multiply
    431.21x = 643.68 × 399.08
  4. Step 4: Simplify right side
    431.21x = 256,881.42
  5. Step 5: Solve for x
    x = 256,881.42/431.21
  6. Step 6: Final answer
    x = 595.73

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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.