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Finding the Fourth Proportional to 211.38, 316.88 and 81.36

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Solution

The fourth proportional to 211.38, 316.88 and 81.36 is: 121.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.38 : 316.88 = 81.36 : x
  2. Step 2: Convert to fraction form
    211.38/316.88 = 81.36/x
  3. Step 3: Cross multiply
    211.38x = 316.88 × 81.36
  4. Step 4: Simplify right side
    211.38x = 25,780.95
  5. Step 5: Solve for x
    x = 25,780.95/211.38
  6. Step 6: Final answer
    x = 121.96

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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.