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Finding the Fourth Proportional to 212.78, 319.39 and 172.68

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Solution

The fourth proportional to 212.78, 319.39 and 172.68 is: 259.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.78 : 319.39 = 172.68 : x
  2. Step 2: Convert to fraction form
    212.78/319.39 = 172.68/x
  3. Step 3: Cross multiply
    212.78x = 319.39 × 172.68
  4. Step 4: Simplify right side
    212.78x = 55,153.40
  5. Step 5: Solve for x
    x = 55,153.40/212.78
  6. Step 6: Final answer
    x = 259.21

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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.