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Finding the Fourth Proportional to 172.18, 258.18 and 91

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Solution

The fourth proportional to 172.18, 258.18 and 91 is: 136.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.18 : 258.18 = 91 : x
  2. Step 2: Convert to fraction form
    172.18/258.18 = 91/x
  3. Step 3: Cross multiply
    172.18x = 258.18 × 91
  4. Step 4: Simplify right side
    172.18x = 23,494.38
  5. Step 5: Solve for x
    x = 23,494.38/172.18
  6. Step 6: Final answer
    x = 136.45

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.