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Finding the Fourth Proportional to 124.72, 172.05 and 91.90

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Solution

The fourth proportional to 124.72, 172.05 and 91.90 is: 126.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    124.72 : 172.05 = 91.90 : x
  2. Step 2: Convert to fraction form
    124.72/172.05 = 91.90/x
  3. Step 3: Cross multiply
    124.72x = 172.05 × 91.90
  4. Step 4: Simplify right side
    124.72x = 15,811.40
  5. Step 5: Solve for x
    x = 15,811.40/124.72
  6. Step 6: Final answer
    x = 126.78

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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.