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Finding the Fourth Proportional to 1,190.40, 1,781.31 and 728.28

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Solution

The fourth proportional to 1,190.40, 1,781.31 and 728.28 is: 1,089.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,190.40 : 1,781.31 = 728.28 : x
  2. Step 2: Convert to fraction form
    1,190.40/1,781.31 = 728.28/x
  3. Step 3: Cross multiply
    1,190.40x = 1,781.31 × 728.28
  4. Step 4: Simplify right side
    1,190.40x = 1,297,292.45
  5. Step 5: Solve for x
    x = 1,297,292.45/1,190.40
  6. Step 6: Final answer
    x = 1,089.80

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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.