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Finding the Fourth Proportional to 211.51, 291.88 and 128.61

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Solution

The fourth proportional to 211.51, 291.88 and 128.61 is: 177.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.51 : 291.88 = 128.61 : x
  2. Step 2: Convert to fraction form
    211.51/291.88 = 128.61/x
  3. Step 3: Cross multiply
    211.51x = 291.88 × 128.61
  4. Step 4: Simplify right side
    211.51x = 37,539.31
  5. Step 5: Solve for x
    x = 37,539.31/211.51
  6. Step 6: Final answer
    x = 177.48

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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.