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Finding the Fourth Proportional to 990.72, 1,367.28 and 636.84

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Solution

The fourth proportional to 990.72, 1,367.28 and 636.84 is: 878.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.72 : 1,367.28 = 636.84 : x
  2. Step 2: Convert to fraction form
    990.72/1,367.28 = 636.84/x
  3. Step 3: Cross multiply
    990.72x = 1,367.28 × 636.84
  4. Step 4: Simplify right side
    990.72x = 870,738.60
  5. Step 5: Solve for x
    x = 870,738.60/990.72
  6. Step 6: Final answer
    x = 878.89

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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.