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Finding the Fourth Proportional to 211.98, 318.09 and 90.30

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Solution

The fourth proportional to 211.98, 318.09 and 90.30 is: 135.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.98 : 318.09 = 90.30 : x
  2. Step 2: Convert to fraction form
    211.98/318.09 = 90.30/x
  3. Step 3: Cross multiply
    211.98x = 318.09 × 90.30
  4. Step 4: Simplify right side
    211.98x = 28,723.53
  5. Step 5: Solve for x
    x = 28,723.53/211.98
  6. Step 6: Final answer
    x = 135.50

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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.