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Finding the Fourth Proportional to 378.99, 522.79 and 221.61

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Solution

The fourth proportional to 378.99, 522.79 and 221.61 is: 305.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    378.99 : 522.79 = 221.61 : x
  2. Step 2: Convert to fraction form
    378.99/522.79 = 221.61/x
  3. Step 3: Cross multiply
    378.99x = 522.79 × 221.61
  4. Step 4: Simplify right side
    378.99x = 115,851.77
  5. Step 5: Solve for x
    x = 115,851.77/378.99
  6. Step 6: Final answer
    x = 305.69

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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.