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Finding the Fourth Proportional to 661.20, 912.36 and 399.24

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Solution

The fourth proportional to 661.20, 912.36 and 399.24 is: 550.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.20 : 912.36 = 399.24 : x
  2. Step 2: Convert to fraction form
    661.20/912.36 = 399.24/x
  3. Step 3: Cross multiply
    661.20x = 912.36 × 399.24
  4. Step 4: Simplify right side
    661.20x = 364,250.61
  5. Step 5: Solve for x
    x = 364,250.61/661.20
  6. Step 6: Final answer
    x = 550.89

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.