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Finding the Fourth Proportional to 871.63, 1,305.39 and 687.80

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Solution

The fourth proportional to 871.63, 1,305.39 and 687.80 is: 1,030.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.63 : 1,305.39 = 687.80 : x
  2. Step 2: Convert to fraction form
    871.63/1,305.39 = 687.80/x
  3. Step 3: Cross multiply
    871.63x = 1,305.39 × 687.80
  4. Step 4: Simplify right side
    871.63x = 897,837.28
  5. Step 5: Solve for x
    x = 897,837.28/871.63
  6. Step 6: Final answer
    x = 1,030.07

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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.