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Finding the Fourth Proportional to 211.98, 317.58 and 138.72

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Solution

The fourth proportional to 211.98, 317.58 and 138.72 is: 207.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.98 : 317.58 = 138.72 : x
  2. Step 2: Convert to fraction form
    211.98/317.58 = 138.72/x
  3. Step 3: Cross multiply
    211.98x = 317.58 × 138.72
  4. Step 4: Simplify right side
    211.98x = 44,054.70
  5. Step 5: Solve for x
    x = 44,054.70/211.98
  6. Step 6: Final answer
    x = 207.82

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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.