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Finding the Fourth Proportional to 121.21, 167.21 and 72

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Solution

The fourth proportional to 121.21, 167.21 and 72 is: 99.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.21 : 167.21 = 72 : x
  2. Step 2: Convert to fraction form
    121.21/167.21 = 72/x
  3. Step 3: Cross multiply
    121.21x = 167.21 × 72
  4. Step 4: Simplify right side
    121.21x = 12,039.12
  5. Step 5: Solve for x
    x = 12,039.12/121.21
  6. Step 6: Final answer
    x = 99.32

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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.