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Finding the Fourth Proportional to 211.52, 291.78 and 128.60

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Solution

The fourth proportional to 211.52, 291.78 and 128.60 is: 177.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.52 : 291.78 = 128.60 : x
  2. Step 2: Convert to fraction form
    211.52/291.78 = 128.60/x
  3. Step 3: Cross multiply
    211.52x = 291.78 × 128.60
  4. Step 4: Simplify right side
    211.52x = 37,521.45
  5. Step 5: Solve for x
    x = 37,521.45/211.52
  6. Step 6: Final answer
    x = 177.39

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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.