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Finding the Fourth Proportional to 919.87, 1,378.43 and 787.31

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Solution

The fourth proportional to 919.87, 1,378.43 and 787.31 is: 1,179.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.87 : 1,378.43 = 787.31 : x
  2. Step 2: Convert to fraction form
    919.87/1,378.43 = 787.31/x
  3. Step 3: Cross multiply
    919.87x = 1,378.43 × 787.31
  4. Step 4: Simplify right side
    919.87x = 1,085,240.89
  5. Step 5: Solve for x
    x = 1,085,240.89/919.87
  6. Step 6: Final answer
    x = 1,179.78

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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.