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Finding the Fourth Proportional to 212.15, 318.31 and 90.50

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Solution

The fourth proportional to 212.15, 318.31 and 90.50 is: 135.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.15 : 318.31 = 90.50 : x
  2. Step 2: Convert to fraction form
    212.15/318.31 = 90.50/x
  3. Step 3: Cross multiply
    212.15x = 318.31 × 90.50
  4. Step 4: Simplify right side
    212.15x = 28,805.24
  5. Step 5: Solve for x
    x = 28,805.24/212.15
  6. Step 6: Final answer
    x = 135.78

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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.