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Finding the Fourth Proportional to 231.80, 319.90 and 138.55

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Solution

The fourth proportional to 231.80, 319.90 and 138.55 is: 191.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    231.80 : 319.90 = 138.55 : x
  2. Step 2: Convert to fraction form
    231.80/319.90 = 138.55/x
  3. Step 3: Cross multiply
    231.80x = 319.90 × 138.55
  4. Step 4: Simplify right side
    231.80x = 44,322.76
  5. Step 5: Solve for x
    x = 44,322.76/231.80
  6. Step 6: Final answer
    x = 191.21

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.