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Finding the Fourth Proportional to 214.28, 321.42 and 86

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Solution

The fourth proportional to 214.28, 321.42 and 86 is: 129

Step by Step Solution

  1. Step 1: Write the proportion equation
    214.28 : 321.42 = 86 : x
  2. Step 2: Convert to fraction form
    214.28/321.42 = 86/x
  3. Step 3: Cross multiply
    214.28x = 321.42 × 86
  4. Step 4: Simplify right side
    214.28x = 27,642.12
  5. Step 5: Solve for x
    x = 27,642.12/214.28
  6. Step 6: Final answer
    x = 129

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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.