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Finding the Fourth Proportional to 124.91, 172.40 and 78.31

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Solution

The fourth proportional to 124.91, 172.40 and 78.31 is: 108.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    124.91 : 172.40 = 78.31 : x
  2. Step 2: Convert to fraction form
    124.91/172.40 = 78.31/x
  3. Step 3: Cross multiply
    124.91x = 172.40 × 78.31
  4. Step 4: Simplify right side
    124.91x = 13,500.64
  5. Step 5: Solve for x
    x = 13,500.64/124.91
  6. Step 6: Final answer
    x = 108.08

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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.