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Finding the Fourth Proportional to 85.21, 127.78 and 31.07

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Solution

The fourth proportional to 85.21, 127.78 and 31.07 is: 46.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.21 : 127.78 = 31.07 : x
  2. Step 2: Convert to fraction form
    85.21/127.78 = 31.07/x
  3. Step 3: Cross multiply
    85.21x = 127.78 × 31.07
  4. Step 4: Simplify right side
    85.21x = 3,970.12
  5. Step 5: Solve for x
    x = 3,970.12/85.21
  6. Step 6: Final answer
    x = 46.59

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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.