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Finding the Fourth Proportional to 211.86, 317.79 and 138.87

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Solution

The fourth proportional to 211.86, 317.79 and 138.87 is: 208.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.86 : 317.79 = 138.87 : x
  2. Step 2: Convert to fraction form
    211.86/317.79 = 138.87/x
  3. Step 3: Cross multiply
    211.86x = 317.79 × 138.87
  4. Step 4: Simplify right side
    211.86x = 44,131.50
  5. Step 5: Solve for x
    x = 44,131.50/211.86
  6. Step 6: Final answer
    x = 208.31

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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.