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Finding the Fourth Proportional to 312.78, 431.59 and 186.71

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Solution

The fourth proportional to 312.78, 431.59 and 186.71 is: 257.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.78 : 431.59 = 186.71 : x
  2. Step 2: Convert to fraction form
    312.78/431.59 = 186.71/x
  3. Step 3: Cross multiply
    312.78x = 431.59 × 186.71
  4. Step 4: Simplify right side
    312.78x = 80,581.09
  5. Step 5: Solve for x
    x = 80,581.09/312.78
  6. Step 6: Final answer
    x = 257.63

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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.