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Finding the Fourth Proportional to 211.68, 291.96 and 128.76

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Solution

The fourth proportional to 211.68, 291.96 and 128.76 is: 177.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.68 : 291.96 = 128.76 : x
  2. Step 2: Convert to fraction form
    211.68/291.96 = 128.76/x
  3. Step 3: Cross multiply
    211.68x = 291.96 × 128.76
  4. Step 4: Simplify right side
    211.68x = 37,592.77
  5. Step 5: Solve for x
    x = 37,592.77/211.68
  6. Step 6: Final answer
    x = 177.59

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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.