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Finding the Fourth Proportional to 214.40, 321.30 and 86

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Solution

The fourth proportional to 214.40, 321.30 and 86 is: 128.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    214.40 : 321.30 = 86 : x
  2. Step 2: Convert to fraction form
    214.40/321.30 = 86/x
  3. Step 3: Cross multiply
    214.40x = 321.30 × 86
  4. Step 4: Simplify right side
    214.40x = 27,631.80
  5. Step 5: Solve for x
    x = 27,631.80/214.40
  6. Step 6: Final answer
    x = 128.88

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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.