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Finding the Fourth Proportional to 211.69, 317.48 and 81.65

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Solution

The fourth proportional to 211.69, 317.48 and 81.65 is: 122.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.69 : 317.48 = 81.65 : x
  2. Step 2: Convert to fraction form
    211.69/317.48 = 81.65/x
  3. Step 3: Cross multiply
    211.69x = 317.48 × 81.65
  4. Step 4: Simplify right side
    211.69x = 25,920.86
  5. Step 5: Solve for x
    x = 25,920.86/211.69
  6. Step 6: Final answer
    x = 122.45

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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.