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Finding the Fourth Proportional to 399.78, 599.64 and 111.21

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Solution

The fourth proportional to 399.78, 599.64 and 111.21 is: 166.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.78 : 599.64 = 111.21 : x
  2. Step 2: Convert to fraction form
    399.78/599.64 = 111.21/x
  3. Step 3: Cross multiply
    399.78x = 599.64 × 111.21
  4. Step 4: Simplify right side
    399.78x = 66,685.96
  5. Step 5: Solve for x
    x = 66,685.96/399.78
  6. Step 6: Final answer
    x = 166.81

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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.