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Finding the Fourth Proportional to 643.70, 965.70 and 278.90

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Solution

The fourth proportional to 643.70, 965.70 and 278.90 is: 418.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.70 : 965.70 = 278.90 : x
  2. Step 2: Convert to fraction form
    643.70/965.70 = 278.90/x
  3. Step 3: Cross multiply
    643.70x = 965.70 × 278.90
  4. Step 4: Simplify right side
    643.70x = 269,328.90
  5. Step 5: Solve for x
    x = 269,328.90/643.70
  6. Step 6: Final answer
    x = 418.41

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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.