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Finding the Fourth Proportional to 991.36, 1,367.84 and 641.98

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Solution

The fourth proportional to 991.36, 1,367.84 and 641.98 is: 885.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.36 : 1,367.84 = 641.98 : x
  2. Step 2: Convert to fraction form
    991.36/1,367.84 = 641.98/x
  3. Step 3: Cross multiply
    991.36x = 1,367.84 × 641.98
  4. Step 4: Simplify right side
    991.36x = 878,125.92
  5. Step 5: Solve for x
    x = 878,125.92/991.36
  6. Step 6: Final answer
    x = 885.78

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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.