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Finding the Fourth Proportional to 920.12, 1,378.80 and 787.56

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Solution

The fourth proportional to 920.12, 1,378.80 and 787.56 is: 1,180.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.12 : 1,378.80 = 787.56 : x
  2. Step 2: Convert to fraction form
    920.12/1,378.80 = 787.56/x
  3. Step 3: Cross multiply
    920.12x = 1,378.80 × 787.56
  4. Step 4: Simplify right side
    920.12x = 1,085,880.83
  5. Step 5: Solve for x
    x = 1,085,880.83/920.12
  6. Step 6: Final answer
    x = 1,180.15

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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.