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Finding the Fourth Proportional to 211.65, 291.98 and 128.74

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Solution

The fourth proportional to 211.65, 291.98 and 128.74 is: 177.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.65 : 291.98 = 128.74 : x
  2. Step 2: Convert to fraction form
    211.65/291.98 = 128.74/x
  3. Step 3: Cross multiply
    211.65x = 291.98 × 128.74
  4. Step 4: Simplify right side
    211.65x = 37,589.10
  5. Step 5: Solve for x
    x = 37,589.10/211.65
  6. Step 6: Final answer
    x = 177.60

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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.