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Finding the Fourth Proportional to 85.21, 127.81 and 21.08

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Solution

The fourth proportional to 85.21, 127.81 and 21.08 is: 31.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.21 : 127.81 = 21.08 : x
  2. Step 2: Convert to fraction form
    85.21/127.81 = 21.08/x
  3. Step 3: Cross multiply
    85.21x = 127.81 × 21.08
  4. Step 4: Simplify right side
    85.21x = 2,694.13
  5. Step 5: Solve for x
    x = 2,694.13/85.21
  6. Step 6: Final answer
    x = 31.62

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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.