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Finding the Fourth Proportional to 290.78, 438.20 and 261.92

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Solution

The fourth proportional to 290.78, 438.20 and 261.92 is: 394.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    290.78 : 438.20 = 261.92 : x
  2. Step 2: Convert to fraction form
    290.78/438.20 = 261.92/x
  3. Step 3: Cross multiply
    290.78x = 438.20 × 261.92
  4. Step 4: Simplify right side
    290.78x = 114,769.84
  5. Step 5: Solve for x
    x = 114,769.84/290.78
  6. Step 6: Final answer
    x = 394.70

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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.