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Finding the Fourth Proportional to 207.42, 286.21 and 128.71

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Solution

The fourth proportional to 207.42, 286.21 and 128.71 is: 177.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.42 : 286.21 = 128.71 : x
  2. Step 2: Convert to fraction form
    207.42/286.21 = 128.71/x
  3. Step 3: Cross multiply
    207.42x = 286.21 × 128.71
  4. Step 4: Simplify right side
    207.42x = 36,839.05
  5. Step 5: Solve for x
    x = 36,839.05/207.42
  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.