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Finding the Fourth Proportional to 919.20, 1,378.80 and 553.80

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Solution

The fourth proportional to 919.20, 1,378.80 and 553.80 is: 830.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.20 : 1,378.80 = 553.80 : x
  2. Step 2: Convert to fraction form
    919.20/1,378.80 = 553.80/x
  3. Step 3: Cross multiply
    919.20x = 1,378.80 × 553.80
  4. Step 4: Simplify right side
    919.20x = 763,579.44
  5. Step 5: Solve for x
    x = 763,579.44/919.20
  6. Step 6: Final answer
    x = 830.70

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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.