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Finding the Fourth Proportional to 221.36, 305.45 and 128.13

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Solution

The fourth proportional to 221.36, 305.45 and 128.13 is: 176.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.36 : 305.45 = 128.13 : x
  2. Step 2: Convert to fraction form
    221.36/305.45 = 128.13/x
  3. Step 3: Cross multiply
    221.36x = 305.45 × 128.13
  4. Step 4: Simplify right side
    221.36x = 39,136.67
  5. Step 5: Solve for x
    x = 39,136.67/221.36
  6. Step 6: Final answer
    x = 176.80

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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.