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Finding the Fourth Proportional to 211.25, 291.45 and 128.39

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Solution

The fourth proportional to 211.25, 291.45 and 128.39 is: 177.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.25 : 291.45 = 128.39 : x
  2. Step 2: Convert to fraction form
    211.25/291.45 = 128.39/x
  3. Step 3: Cross multiply
    211.25x = 291.45 × 128.39
  4. Step 4: Simplify right side
    211.25x = 37,419.27
  5. Step 5: Solve for x
    x = 37,419.27/211.25
  6. Step 6: Final answer
    x = 177.13

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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.