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Finding the Fourth Proportional to 214.79, 321.30 and 128.12

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Solution

The fourth proportional to 214.79, 321.30 and 128.12 is: 191.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    214.79 : 321.30 = 128.12 : x
  2. Step 2: Convert to fraction form
    214.79/321.30 = 128.12/x
  3. Step 3: Cross multiply
    214.79x = 321.30 × 128.12
  4. Step 4: Simplify right side
    214.79x = 41,163.35
  5. Step 5: Solve for x
    x = 41,163.35/214.79
  6. Step 6: Final answer
    x = 191.65

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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.