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Finding the Fourth Proportional to 123.21, 169.71 and 86.31

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Solution

The fourth proportional to 123.21, 169.71 and 86.31 is: 118.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.21 : 169.71 = 86.31 : x
  2. Step 2: Convert to fraction form
    123.21/169.71 = 86.31/x
  3. Step 3: Cross multiply
    123.21x = 169.71 × 86.31
  4. Step 4: Simplify right side
    123.21x = 14,647.67
  5. Step 5: Solve for x
    x = 14,647.67/123.21
  6. Step 6: Final answer
    x = 118.88

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.