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Finding the Fourth Proportional to 919.64, 1,379.15 and 399.31

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Solution

The fourth proportional to 919.64, 1,379.15 and 399.31 is: 598.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.64 : 1,379.15 = 399.31 : x
  2. Step 2: Convert to fraction form
    919.64/1,379.15 = 399.31/x
  3. Step 3: Cross multiply
    919.64x = 1,379.15 × 399.31
  4. Step 4: Simplify right side
    919.64x = 550,708.39
  5. Step 5: Solve for x
    x = 550,708.39/919.64
  6. Step 6: Final answer
    x = 598.83

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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.