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Finding the Fourth Proportional to 1,918.71, 2,878.35 and 685.83

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Solution

The fourth proportional to 1,918.71, 2,878.35 and 685.83 is: 1,028.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,918.71 : 2,878.35 = 685.83 : x
  2. Step 2: Convert to fraction form
    1,918.71/2,878.35 = 685.83/x
  3. Step 3: Cross multiply
    1,918.71x = 2,878.35 × 685.83
  4. Step 4: Simplify right side
    1,918.71x = 1,974,058.78
  5. Step 5: Solve for x
    x = 1,974,058.78/1,918.71
  6. Step 6: Final answer
    x = 1,028.85

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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.