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Finding the Fourth Proportional to 216.88, 299.31 and 128.39

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Solution

The fourth proportional to 216.88, 299.31 and 128.39 is: 177.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    216.88 : 299.31 = 128.39 : x
  2. Step 2: Convert to fraction form
    216.88/299.31 = 128.39/x
  3. Step 3: Cross multiply
    216.88x = 299.31 × 128.39
  4. Step 4: Simplify right side
    216.88x = 38,426.91
  5. Step 5: Solve for x
    x = 38,426.91/216.88
  6. Step 6: Final answer
    x = 177.18

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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.