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Finding the Fourth Proportional to 90.86, 125.18 and 79.31

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Solution

The fourth proportional to 90.86, 125.18 and 79.31 is: 109.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.86 : 125.18 = 79.31 : x
  2. Step 2: Convert to fraction form
    90.86/125.18 = 79.31/x
  3. Step 3: Cross multiply
    90.86x = 125.18 × 79.31
  4. Step 4: Simplify right side
    90.86x = 9,928.24
  5. Step 5: Solve for x
    x = 9,928.24/90.86
  6. Step 6: Final answer
    x = 109.28

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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.