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Finding the Fourth Proportional to 213.78, 320.90 and 127.20

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Solution

The fourth proportional to 213.78, 320.90 and 127.20 is: 190.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.78 : 320.90 = 127.20 : x
  2. Step 2: Convert to fraction form
    213.78/320.90 = 127.20/x
  3. Step 3: Cross multiply
    213.78x = 320.90 × 127.20
  4. Step 4: Simplify right side
    213.78x = 40,817.84
  5. Step 5: Solve for x
    x = 40,817.84/213.78
  6. Step 6: Final answer
    x = 190.93

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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.