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Finding the Fourth Proportional to 221.42, 305.53 and 128.15

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Solution

The fourth proportional to 221.42, 305.53 and 128.15 is: 176.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.42 : 305.53 = 128.15 : x
  2. Step 2: Convert to fraction form
    221.42/305.53 = 128.15/x
  3. Step 3: Cross multiply
    221.42x = 305.53 × 128.15
  4. Step 4: Simplify right side
    221.42x = 39,153.67
  5. Step 5: Solve for x
    x = 39,153.67/221.42
  6. Step 6: Final answer
    x = 176.83

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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.