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Finding the Fourth Proportional to 862.80, 1,287.57 and 857.87

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Solution

The fourth proportional to 862.80, 1,287.57 and 857.87 is: 1,280.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    862.80 : 1,287.57 = 857.87 : x
  2. Step 2: Convert to fraction form
    862.80/1,287.57 = 857.87/x
  3. Step 3: Cross multiply
    862.80x = 1,287.57 × 857.87
  4. Step 4: Simplify right side
    862.80x = 1,104,568.68
  5. Step 5: Solve for x
    x = 1,104,568.68/862.80
  6. Step 6: Final answer
    x = 1,280.21

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.