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Finding the Fourth Proportional to 1,918.60, 2,878.17 and 686.21

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Solution

The fourth proportional to 1,918.60, 2,878.17 and 686.21 is: 1,029.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,918.60 : 2,878.17 = 686.21 : x
  2. Step 2: Convert to fraction form
    1,918.60/2,878.17 = 686.21/x
  3. Step 3: Cross multiply
    1,918.60x = 2,878.17 × 686.21
  4. Step 4: Simplify right side
    1,918.60x = 1,975,025.60
  5. Step 5: Solve for x
    x = 1,975,025.60/1,918.60
  6. Step 6: Final answer
    x = 1,029.41

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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.