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Finding the Fourth Proportional to 211.14, 316.65 and 81.05

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Solution

The fourth proportional to 211.14, 316.65 and 81.05 is: 121.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.14 : 316.65 = 81.05 : x
  2. Step 2: Convert to fraction form
    211.14/316.65 = 81.05/x
  3. Step 3: Cross multiply
    211.14x = 316.65 × 81.05
  4. Step 4: Simplify right side
    211.14x = 25,663.20
  5. Step 5: Solve for x
    x = 25,663.20/211.14
  6. Step 6: Final answer
    x = 121.55

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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.