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Finding the Fourth Proportional to 1,378.40, 2,067.14 and 685.40

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Solution

The fourth proportional to 1,378.40, 2,067.14 and 685.40 is: 1,027.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.40 : 2,067.14 = 685.40 : x
  2. Step 2: Convert to fraction form
    1,378.40/2,067.14 = 685.40/x
  3. Step 3: Cross multiply
    1,378.40x = 2,067.14 × 685.40
  4. Step 4: Simplify right side
    1,378.40x = 1,416,803.99
  5. Step 5: Solve for x
    x = 1,416,803.99/1,378.40
  6. Step 6: Final answer
    x = 1,027.87

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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.