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Finding the Fourth Proportional to 121.79, 167.97 and 90.72

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Solution

The fourth proportional to 121.79, 167.97 and 90.72 is: 125.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.79 : 167.97 = 90.72 : x
  2. Step 2: Convert to fraction form
    121.79/167.97 = 90.72/x
  3. Step 3: Cross multiply
    121.79x = 167.97 × 90.72
  4. Step 4: Simplify right side
    121.79x = 15,238.24
  5. Step 5: Solve for x
    x = 15,238.24/121.79
  6. Step 6: Final answer
    x = 125.12

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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.