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Finding the Fourth Proportional to 399.40, 548.57 and 389.80

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Solution

The fourth proportional to 399.40, 548.57 and 389.80 is: 535.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.40 : 548.57 = 389.80 : x
  2. Step 2: Convert to fraction form
    399.40/548.57 = 389.80/x
  3. Step 3: Cross multiply
    399.40x = 548.57 × 389.80
  4. Step 4: Simplify right side
    399.40x = 213,832.59
  5. Step 5: Solve for x
    x = 213,832.59/399.40
  6. Step 6: Final answer
    x = 535.38

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.