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Finding the Fourth Proportional to 921.82, 1,271.86 and 641.74

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Solution

The fourth proportional to 921.82, 1,271.86 and 641.74 is: 885.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.82 : 1,271.86 = 641.74 : x
  2. Step 2: Convert to fraction form
    921.82/1,271.86 = 641.74/x
  3. Step 3: Cross multiply
    921.82x = 1,271.86 × 641.74
  4. Step 4: Simplify right side
    921.82x = 816,203.44
  5. Step 5: Solve for x
    x = 816,203.44/921.82
  6. Step 6: Final answer
    x = 885.43

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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.