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Finding the Fourth Proportional to 1,919.28, 2,878.56 and 686.64

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Solution

The fourth proportional to 1,919.28, 2,878.56 and 686.64 is: 1,029.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,919.28 : 2,878.56 = 686.64 : x
  2. Step 2: Convert to fraction form
    1,919.28/2,878.56 = 686.64/x
  3. Step 3: Cross multiply
    1,919.28x = 2,878.56 × 686.64
  4. Step 4: Simplify right side
    1,919.28x = 1,976,534.44
  5. Step 5: Solve for x
    x = 1,976,534.44/1,919.28
  6. Step 6: Final answer
    x = 1,029.83

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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.