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Finding the Fourth Proportional to 2,079.80, 3,121.32 and 781.64

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Solution

The fourth proportional to 2,079.80, 3,121.32 and 781.64 is: 1,173.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,079.80 : 3,121.32 = 781.64 : x
  2. Step 2: Convert to fraction form
    2,079.80/3,121.32 = 781.64/x
  3. Step 3: Cross multiply
    2,079.80x = 3,121.32 × 781.64
  4. Step 4: Simplify right side
    2,079.80x = 2,439,748.56
  5. Step 5: Solve for x
    x = 2,439,748.56/2,079.80
  6. Step 6: Final answer
    x = 1,173.07

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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.