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Finding the Fourth Proportional to 211.21, 291.36 and 128.28

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Solution

The fourth proportional to 211.21, 291.36 and 128.28 is: 176.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.21 : 291.36 = 128.28 : x
  2. Step 2: Convert to fraction form
    211.21/291.36 = 128.28/x
  3. Step 3: Cross multiply
    211.21x = 291.36 × 128.28
  4. Step 4: Simplify right side
    211.21x = 37,377.23
  5. Step 5: Solve for x
    x = 37,377.23/211.21
  6. Step 6: Final answer
    x = 176.97

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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.