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Finding the Fourth Proportional to 386.45, 579.80 and 212.90

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Solution

The fourth proportional to 386.45, 579.80 and 212.90 is: 319.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.45 : 579.80 = 212.90 : x
  2. Step 2: Convert to fraction form
    386.45/579.80 = 212.90/x
  3. Step 3: Cross multiply
    386.45x = 579.80 × 212.90
  4. Step 4: Simplify right side
    386.45x = 123,437.05
  5. Step 5: Solve for x
    x = 123,437.05/386.45
  6. Step 6: Final answer
    x = 319.42

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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.