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Finding the Fourth Proportional to 919.71, 1,379.81 and 399.49

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Solution

The fourth proportional to 919.71, 1,379.81 and 399.49 is: 599.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.71 : 1,379.81 = 399.49 : x
  2. Step 2: Convert to fraction form
    919.71/1,379.81 = 399.49/x
  3. Step 3: Cross multiply
    919.71x = 1,379.81 × 399.49
  4. Step 4: Simplify right side
    919.71x = 551,220.30
  5. Step 5: Solve for x
    x = 551,220.30/919.71
  6. Step 6: Final answer
    x = 599.34

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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.