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Finding the Fourth Proportional to 1,991.20, 2,986.80 and 1,127.20

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Solution

The fourth proportional to 1,991.20, 2,986.80 and 1,127.20 is: 1,690.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,991.20 : 2,986.80 = 1,127.20 : x
  2. Step 2: Convert to fraction form
    1,991.20/2,986.80 = 1,127.20/x
  3. Step 3: Cross multiply
    1,991.20x = 2,986.80 × 1,127.20
  4. Step 4: Simplify right side
    1,991.20x = 3,366,720.96
  5. Step 5: Solve for x
    x = 3,366,720.96/1,991.20
  6. Step 6: Final answer
    x = 1,690.80

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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.