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Finding the Fourth Proportional to 142.81, 212.99 and 121.28

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Solution

The fourth proportional to 142.81, 212.99 and 121.28 is: 180.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.81 : 212.99 = 121.28 : x
  2. Step 2: Convert to fraction form
    142.81/212.99 = 121.28/x
  3. Step 3: Cross multiply
    142.81x = 212.99 × 121.28
  4. Step 4: Simplify right side
    142.81x = 25,831.43
  5. Step 5: Solve for x
    x = 25,831.43/142.81
  6. Step 6: Final answer
    x = 180.88

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.