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Finding the Fourth Proportional to 212.13, 318.11 and 90.40

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Solution

The fourth proportional to 212.13, 318.11 and 90.40 is: 135.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.13 : 318.11 = 90.40 : x
  2. Step 2: Convert to fraction form
    212.13/318.11 = 90.40/x
  3. Step 3: Cross multiply
    212.13x = 318.11 × 90.40
  4. Step 4: Simplify right side
    212.13x = 28,757.14
  5. Step 5: Solve for x
    x = 28,757.14/212.13
  6. Step 6: Final answer
    x = 135.56

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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.