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Finding the Fourth Proportional to 212.12, 318.20 and 90.40

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Solution

The fourth proportional to 212.12, 318.20 and 90.40 is: 135.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.12 : 318.20 = 90.40 : x
  2. Step 2: Convert to fraction form
    212.12/318.20 = 90.40/x
  3. Step 3: Cross multiply
    212.12x = 318.20 × 90.40
  4. Step 4: Simplify right side
    212.12x = 28,765.28
  5. Step 5: Solve for x
    x = 28,765.28/212.12
  6. Step 6: Final answer
    x = 135.61

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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.