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Finding the Fourth Proportional to 211.37, 317.09 and 81.40

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Solution

The fourth proportional to 211.37, 317.09 and 81.40 is: 122.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.37 : 317.09 = 81.40 : x
  2. Step 2: Convert to fraction form
    211.37/317.09 = 81.40/x
  3. Step 3: Cross multiply
    211.37x = 317.09 × 81.40
  4. Step 4: Simplify right side
    211.37x = 25,811.13
  5. Step 5: Solve for x
    x = 25,811.13/211.37
  6. Step 6: Final answer
    x = 122.11

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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.