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Finding the Fourth Proportional to 216.21, 298.35 and 128.88

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Solution

The fourth proportional to 216.21, 298.35 and 128.88 is: 177.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    216.21 : 298.35 = 128.88 : x
  2. Step 2: Convert to fraction form
    216.21/298.35 = 128.88/x
  3. Step 3: Cross multiply
    216.21x = 298.35 × 128.88
  4. Step 4: Simplify right side
    216.21x = 38,451.35
  5. Step 5: Solve for x
    x = 38,451.35/216.21
  6. Step 6: Final answer
    x = 177.84

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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.