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Finding the Fourth Proportional to 286.90, 431.90 and 261.38

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Solution

The fourth proportional to 286.90, 431.90 and 261.38 is: 393.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    286.90 : 431.90 = 261.38 : x
  2. Step 2: Convert to fraction form
    286.90/431.90 = 261.38/x
  3. Step 3: Cross multiply
    286.90x = 431.90 × 261.38
  4. Step 4: Simplify right side
    286.90x = 112,889.79
  5. Step 5: Solve for x
    x = 112,889.79/286.90
  6. Step 6: Final answer
    x = 393.48

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.