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Finding the Fourth Proportional to 427.32, 640.86 and 138.78

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Solution

The fourth proportional to 427.32, 640.86 and 138.78 is: 208.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.32 : 640.86 = 138.78 : x
  2. Step 2: Convert to fraction form
    427.32/640.86 = 138.78/x
  3. Step 3: Cross multiply
    427.32x = 640.86 × 138.78
  4. Step 4: Simplify right side
    427.32x = 88,938.55
  5. Step 5: Solve for x
    x = 88,938.55/427.32
  6. Step 6: Final answer
    x = 208.13

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