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Finding the Fourth Proportional to 211.61, 317.21 and 81.52

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Solution

The fourth proportional to 211.61, 317.21 and 81.52 is: 122.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.61 : 317.21 = 81.52 : x
  2. Step 2: Convert to fraction form
    211.61/317.21 = 81.52/x
  3. Step 3: Cross multiply
    211.61x = 317.21 × 81.52
  4. Step 4: Simplify right side
    211.61x = 25,858.96
  5. Step 5: Solve for x
    x = 25,858.96/211.61
  6. Step 6: Final answer
    x = 122.20

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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.