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Finding the Fourth Proportional to 312.80, 431.61 and 194.78

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Solution

The fourth proportional to 312.80, 431.61 and 194.78 is: 268.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.80 : 431.61 = 194.78 : x
  2. Step 2: Convert to fraction form
    312.80/431.61 = 194.78/x
  3. Step 3: Cross multiply
    312.80x = 431.61 × 194.78
  4. Step 4: Simplify right side
    312.80x = 84,066.84
  5. Step 5: Solve for x
    x = 84,066.84/312.80
  6. Step 6: Final answer
    x = 268.76

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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.