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Finding the Fourth Proportional to 992.31, 1,489.82 and 639.96

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Solution

The fourth proportional to 992.31, 1,489.82 and 639.96 is: 960.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    992.31 : 1,489.82 = 639.96 : x
  2. Step 2: Convert to fraction form
    992.31/1,489.82 = 639.96/x
  3. Step 3: Cross multiply
    992.31x = 1,489.82 × 639.96
  4. Step 4: Simplify right side
    992.31x = 953,425.21
  5. Step 5: Solve for x
    x = 953,425.21/992.31
  6. Step 6: Final answer
    x = 960.81

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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.