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Finding the Fourth Proportional to 643.05, 964.89 and 399.78

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Solution

The fourth proportional to 643.05, 964.89 and 399.78 is: 599.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.05 : 964.89 = 399.78 : x
  2. Step 2: Convert to fraction form
    643.05/964.89 = 399.78/x
  3. Step 3: Cross multiply
    643.05x = 964.89 × 399.78
  4. Step 4: Simplify right side
    643.05x = 385,743.72
  5. Step 5: Solve for x
    x = 385,743.72/643.05
  6. Step 6: Final answer
    x = 599.87

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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.