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Finding the Fourth Proportional to 991.28, 1,367.85 and 641.97

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Solution

The fourth proportional to 991.28, 1,367.85 and 641.97 is: 885.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.28 : 1,367.85 = 641.97 : x
  2. Step 2: Convert to fraction form
    991.28/1,367.85 = 641.97/x
  3. Step 3: Cross multiply
    991.28x = 1,367.85 × 641.97
  4. Step 4: Simplify right side
    991.28x = 878,118.66
  5. Step 5: Solve for x
    x = 878,118.66/991.28
  6. Step 6: Final answer
    x = 885.84

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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.