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Finding the Fourth Proportional to 211.79, 317.81 and 138.66

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Solution

The fourth proportional to 211.79, 317.81 and 138.66 is: 208.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.79 : 317.81 = 138.66 : x
  2. Step 2: Convert to fraction form
    211.79/317.81 = 138.66/x
  3. Step 3: Cross multiply
    211.79x = 317.81 × 138.66
  4. Step 4: Simplify right side
    211.79x = 44,066.69
  5. Step 5: Solve for x
    x = 44,066.69/211.79
  6. Step 6: Final answer
    x = 208.07

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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.