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Finding the Fourth Proportional to 221.23, 305.30 and 128

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Solution

The fourth proportional to 221.23, 305.30 and 128 is: 176.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.23 : 305.30 = 128 : x
  2. Step 2: Convert to fraction form
    221.23/305.30 = 128/x
  3. Step 3: Cross multiply
    221.23x = 305.30 × 128
  4. Step 4: Simplify right side
    221.23x = 39,078.40
  5. Step 5: Solve for x
    x = 39,078.40/221.23
  6. Step 6: Final answer
    x = 176.64

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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.