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Finding the Fourth Proportional to 211.80, 292.26 and 128.91

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Solution

The fourth proportional to 211.80, 292.26 and 128.91 is: 177.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.80 : 292.26 = 128.91 : x
  2. Step 2: Convert to fraction form
    211.80/292.26 = 128.91/x
  3. Step 3: Cross multiply
    211.80x = 292.26 × 128.91
  4. Step 4: Simplify right side
    211.80x = 37,675.24
  5. Step 5: Solve for x
    x = 37,675.24/211.80
  6. Step 6: Final answer
    x = 177.88

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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.