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Finding the Fourth Proportional to 386.80, 579.58 and 213.21

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Solution

The fourth proportional to 386.80, 579.58 and 213.21 is: 319.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.80 : 579.58 = 213.21 : x
  2. Step 2: Convert to fraction form
    386.80/579.58 = 213.21/x
  3. Step 3: Cross multiply
    386.80x = 579.58 × 213.21
  4. Step 4: Simplify right side
    386.80x = 123,571.72
  5. Step 5: Solve for x
    x = 123,571.72/386.80
  6. Step 6: Final answer
    x = 319.47

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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.