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Finding the Fourth Proportional to 989.28, 1,485.00 and 728.47

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Solution

The fourth proportional to 989.28, 1,485.00 and 728.47 is: 1,093.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.28 : 1,485.00 = 728.47 : x
  2. Step 2: Convert to fraction form
    989.28/1,485.00 = 728.47/x
  3. Step 3: Cross multiply
    989.28x = 1,485.00 × 728.47
  4. Step 4: Simplify right side
    989.28x = 1,081,772.56
  5. Step 5: Solve for x
    x = 1,081,772.56/989.28
  6. Step 6: Final answer
    x = 1,093.50

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.