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Finding the Fourth Proportional to 211.65, 317.47 and 81.67

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Solution

The fourth proportional to 211.65, 317.47 and 81.67 is: 122.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.65 : 317.47 = 81.67 : x
  2. Step 2: Convert to fraction form
    211.65/317.47 = 81.67/x
  3. Step 3: Cross multiply
    211.65x = 317.47 × 81.67
  4. Step 4: Simplify right side
    211.65x = 25,927.77
  5. Step 5: Solve for x
    x = 25,927.77/211.65
  6. Step 6: Final answer
    x = 122.50

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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.