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Finding the Fourth Proportional to 127.71, 175.81 and 121.90

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Solution

The fourth proportional to 127.71, 175.81 and 121.90 is: 167.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    127.71 : 175.81 = 121.90 : x
  2. Step 2: Convert to fraction form
    127.71/175.81 = 121.90/x
  3. Step 3: Cross multiply
    127.71x = 175.81 × 121.90
  4. Step 4: Simplify right side
    127.71x = 21,431.24
  5. Step 5: Solve for x
    x = 21,431.24/127.71
  6. Step 6: Final answer
    x = 167.81

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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.