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Finding the Fourth Proportional to 124.86, 172.32 and 81.21

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Solution

The fourth proportional to 124.86, 172.32 and 81.21 is: 112.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    124.86 : 172.32 = 81.21 : x
  2. Step 2: Convert to fraction form
    124.86/172.32 = 81.21/x
  3. Step 3: Cross multiply
    124.86x = 172.32 × 81.21
  4. Step 4: Simplify right side
    124.86x = 13,994.11
  5. Step 5: Solve for x
    x = 13,994.11/124.86
  6. Step 6: Final answer
    x = 112.08

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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.