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Finding the Fourth Proportional to 643.44, 965.21 and 318.72

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Solution

The fourth proportional to 643.44, 965.21 and 318.72 is: 478.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.44 : 965.21 = 318.72 : x
  2. Step 2: Convert to fraction form
    643.44/965.21 = 318.72/x
  3. Step 3: Cross multiply
    643.44x = 965.21 × 318.72
  4. Step 4: Simplify right side
    643.44x = 307,630.14
  5. Step 5: Solve for x
    x = 307,630.14/643.44
  6. Step 6: Final answer
    x = 478.10

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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.