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Finding the Fourth Proportional to 1,381.20, 1,906.32 and 857.28

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Solution

The fourth proportional to 1,381.20, 1,906.32 and 857.28 is: 1,183.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,381.20 : 1,906.32 = 857.28 : x
  2. Step 2: Convert to fraction form
    1,381.20/1,906.32 = 857.28/x
  3. Step 3: Cross multiply
    1,381.20x = 1,906.32 × 857.28
  4. Step 4: Simplify right side
    1,381.20x = 1,634,250.01
  5. Step 5: Solve for x
    x = 1,634,250.01/1,381.20
  6. Step 6: Final answer
    x = 1,183.21

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.