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Finding the Fourth Proportional to 643.90, 965.76 and 211

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Solution

The fourth proportional to 643.90, 965.76 and 211 is: 316.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.90 : 965.76 = 211 : x
  2. Step 2: Convert to fraction form
    643.90/965.76 = 211/x
  3. Step 3: Cross multiply
    643.90x = 965.76 × 211
  4. Step 4: Simplify right side
    643.90x = 203,775.36
  5. Step 5: Solve for x
    x = 203,775.36/643.90
  6. Step 6: Final answer
    x = 316.47

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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.