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Finding the Fourth Proportional to 81.40, 111.53 and 79.18

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Solution

The fourth proportional to 81.40, 111.53 and 79.18 is: 108.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.40 : 111.53 = 79.18 : x
  2. Step 2: Convert to fraction form
    81.40/111.53 = 79.18/x
  3. Step 3: Cross multiply
    81.40x = 111.53 × 79.18
  4. Step 4: Simplify right side
    81.40x = 8,830.95
  5. Step 5: Solve for x
    x = 8,830.95/81.40
  6. Step 6: Final answer
    x = 108.49

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.