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Finding the Fourth Proportional to 261.78, 392.31 and 218.72

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Solution

The fourth proportional to 261.78, 392.31 and 218.72 is: 327.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.78 : 392.31 = 218.72 : x
  2. Step 2: Convert to fraction form
    261.78/392.31 = 218.72/x
  3. Step 3: Cross multiply
    261.78x = 392.31 × 218.72
  4. Step 4: Simplify right side
    261.78x = 85,804.82
  5. Step 5: Solve for x
    x = 85,804.82/261.78
  6. Step 6: Final answer
    x = 327.77

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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.