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Finding the Fourth Proportional to 820.87, 1,131.93 and 643.50

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Solution

The fourth proportional to 820.87, 1,131.93 and 643.50 is: 887.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.87 : 1,131.93 = 643.50 : x
  2. Step 2: Convert to fraction form
    820.87/1,131.93 = 643.50/x
  3. Step 3: Cross multiply
    820.87x = 1,131.93 × 643.50
  4. Step 4: Simplify right side
    820.87x = 728,396.96
  5. Step 5: Solve for x
    x = 728,396.96/820.87
  6. Step 6: Final answer
    x = 887.35

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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.