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Finding the Fourth Proportional to 82.31, 123.47 and 28.21

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Solution

The fourth proportional to 82.31, 123.47 and 28.21 is: 42.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.31 : 123.47 = 28.21 : x
  2. Step 2: Convert to fraction form
    82.31/123.47 = 28.21/x
  3. Step 3: Cross multiply
    82.31x = 123.47 × 28.21
  4. Step 4: Simplify right side
    82.31x = 3,482.74
  5. Step 5: Solve for x
    x = 3,482.74/82.31
  6. Step 6: Final answer
    x = 42.31

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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.