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Finding the Fourth Proportional to 172.91, 238.64 and 99.21

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Solution

The fourth proportional to 172.91, 238.64 and 99.21 is: 136.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.91 : 238.64 = 99.21 : x
  2. Step 2: Convert to fraction form
    172.91/238.64 = 99.21/x
  3. Step 3: Cross multiply
    172.91x = 238.64 × 99.21
  4. Step 4: Simplify right side
    172.91x = 23,674.98
  5. Step 5: Solve for x
    x = 23,674.98/172.91
  6. Step 6: Final answer
    x = 136.92

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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.