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Finding the Fourth Proportional to 989.42, 1,480.58 and 728.80

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Solution

The fourth proportional to 989.42, 1,480.58 and 728.80 is: 1,090.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.42 : 1,480.58 = 728.80 : x
  2. Step 2: Convert to fraction form
    989.42/1,480.58 = 728.80/x
  3. Step 3: Cross multiply
    989.42x = 1,480.58 × 728.80
  4. Step 4: Simplify right side
    989.42x = 1,079,042.09
  5. Step 5: Solve for x
    x = 1,079,042.09/989.42
  6. Step 6: Final answer
    x = 1,090.59

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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.