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Finding the Fourth Proportional to 121.68, 167.94 and 99.81

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Solution

The fourth proportional to 121.68, 167.94 and 99.81 is: 137.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.68 : 167.94 = 99.81 : x
  2. Step 2: Convert to fraction form
    121.68/167.94 = 99.81/x
  3. Step 3: Cross multiply
    121.68x = 167.94 × 99.81
  4. Step 4: Simplify right side
    121.68x = 16,762.09
  5. Step 5: Solve for x
    x = 16,762.09/121.68
  6. Step 6: Final answer
    x = 137.76

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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.