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Finding the Fourth Proportional to 121.51, 167.72 and 77.86

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Solution

The fourth proportional to 121.51, 167.72 and 77.86 is: 107.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.51 : 167.72 = 77.86 : x
  2. Step 2: Convert to fraction form
    121.51/167.72 = 77.86/x
  3. Step 3: Cross multiply
    121.51x = 167.72 × 77.86
  4. Step 4: Simplify right side
    121.51x = 13,058.68
  5. Step 5: Solve for x
    x = 13,058.68/121.51
  6. Step 6: Final answer
    x = 107.47

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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.