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Finding the Fourth Proportional to 2,079.90, 3,121.20 and 781.35

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Solution

The fourth proportional to 2,079.90, 3,121.20 and 781.35 is: 1,172.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,079.90 : 3,121.20 = 781.35 : x
  2. Step 2: Convert to fraction form
    2,079.90/3,121.20 = 781.35/x
  3. Step 3: Cross multiply
    2,079.90x = 3,121.20 × 781.35
  4. Step 4: Simplify right side
    2,079.90x = 2,438,749.62
  5. Step 5: Solve for x
    x = 2,438,749.62/2,079.90
  6. Step 6: Final answer
    x = 1,172.53

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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.