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Finding the Fourth Proportional to 990, 1,366.92 and 728.40

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Solution

The fourth proportional to 990, 1,366.92 and 728.40 is: 1,005.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    990 : 1,366.92 = 728.40 : x
  2. Step 2: Convert to fraction form
    990/1,366.92 = 728.40/x
  3. Step 3: Cross multiply
    990x = 1,366.92 × 728.40
  4. Step 4: Simplify right side
    990x = 995,664.53
  5. Step 5: Solve for x
    x = 995,664.53/990
  6. Step 6: Final answer
    x = 1,005.72

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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.