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Finding the Fourth Proportional to 211.66, 292.11 and 128.79

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Solution

The fourth proportional to 211.66, 292.11 and 128.79 is: 177.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.66 : 292.11 = 128.79 : x
  2. Step 2: Convert to fraction form
    211.66/292.11 = 128.79/x
  3. Step 3: Cross multiply
    211.66x = 292.11 × 128.79
  4. Step 4: Simplify right side
    211.66x = 37,621.45
  5. Step 5: Solve for x
    x = 37,621.45/211.66
  6. Step 6: Final answer
    x = 177.74

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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.