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Finding the Fourth Proportional to 121.78, 167.98 and 72.64

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Solution

The fourth proportional to 121.78, 167.98 and 72.64 is: 100.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.78 : 167.98 = 72.64 : x
  2. Step 2: Convert to fraction form
    121.78/167.98 = 72.64/x
  3. Step 3: Cross multiply
    121.78x = 167.98 × 72.64
  4. Step 4: Simplify right side
    121.78x = 12,201.47
  5. Step 5: Solve for x
    x = 12,201.47/121.78
  6. Step 6: Final answer
    x = 100.19

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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.