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Finding the Fourth Proportional to 214.67, 321.21 and 128.05

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Solution

The fourth proportional to 214.67, 321.21 and 128.05 is: 191.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    214.67 : 321.21 = 128.05 : x
  2. Step 2: Convert to fraction form
    214.67/321.21 = 128.05/x
  3. Step 3: Cross multiply
    214.67x = 321.21 × 128.05
  4. Step 4: Simplify right side
    214.67x = 41,132.12
  5. Step 5: Solve for x
    x = 41,132.12/214.67
  6. Step 6: Final answer
    x = 191.60

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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.