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Finding the Fourth Proportional to 212.21, 318.31 and 90.39

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Solution

The fourth proportional to 212.21, 318.31 and 90.39 is: 135.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.21 : 318.31 = 90.39 : x
  2. Step 2: Convert to fraction form
    212.21/318.31 = 90.39/x
  3. Step 3: Cross multiply
    212.21x = 318.31 × 90.39
  4. Step 4: Simplify right side
    212.21x = 28,772.04
  5. Step 5: Solve for x
    x = 28,772.04/212.21
  6. Step 6: Final answer
    x = 135.58

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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.