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Finding the Fourth Proportional to 427.21, 640.82 and 138.67

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Solution

The fourth proportional to 427.21, 640.82 and 138.67 is: 208.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.21 : 640.82 = 138.67 : x
  2. Step 2: Convert to fraction form
    427.21/640.82 = 138.67/x
  3. Step 3: Cross multiply
    427.21x = 640.82 × 138.67
  4. Step 4: Simplify right side
    427.21x = 88,862.51
  5. Step 5: Solve for x
    x = 88,862.51/427.21
  6. Step 6: Final answer
    x = 208.01

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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.