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Finding the Fourth Proportional to 820.14, 1,131.80 and 643.31

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Solution

The fourth proportional to 820.14, 1,131.80 and 643.31 is: 887.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.14 : 1,131.80 = 643.31 : x
  2. Step 2: Convert to fraction form
    820.14/1,131.80 = 643.31/x
  3. Step 3: Cross multiply
    820.14x = 1,131.80 × 643.31
  4. Step 4: Simplify right side
    820.14x = 728,098.26
  5. Step 5: Solve for x
    x = 728,098.26/820.14
  6. Step 6: Final answer
    x = 887.77

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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.