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Finding the Fourth Proportional to 221.25, 305.31 and 128.00

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Solution

The fourth proportional to 221.25, 305.31 and 128.00 is: 176.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.25 : 305.31 = 128.00 : x
  2. Step 2: Convert to fraction form
    221.25/305.31 = 128.00/x
  3. Step 3: Cross multiply
    221.25x = 305.31 × 128.00
  4. Step 4: Simplify right side
    221.25x = 39,080.99
  5. Step 5: Solve for x
    x = 39,080.99/221.25
  6. Step 6: Final answer
    x = 176.63

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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.