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Finding the Fourth Proportional to 211.06, 316.72 and 81.07

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Solution

The fourth proportional to 211.06, 316.72 and 81.07 is: 121.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.06 : 316.72 = 81.07 : x
  2. Step 2: Convert to fraction form
    211.06/316.72 = 81.07/x
  3. Step 3: Cross multiply
    211.06x = 316.72 × 81.07
  4. Step 4: Simplify right side
    211.06x = 25,675.34
  5. Step 5: Solve for x
    x = 25,675.34/211.06
  6. Step 6: Final answer
    x = 121.65

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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.