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Finding the Fourth Proportional to 791.32, 1,187.40 and 380.40

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Solution

The fourth proportional to 791.32, 1,187.40 and 380.40 is: 570.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    791.32 : 1,187.40 = 380.40 : x
  2. Step 2: Convert to fraction form
    791.32/1,187.40 = 380.40/x
  3. Step 3: Cross multiply
    791.32x = 1,187.40 × 380.40
  4. Step 4: Simplify right side
    791.32x = 451,686.96
  5. Step 5: Solve for x
    x = 451,686.96/791.32
  6. Step 6: Final answer
    x = 570.80

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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.