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Finding the Fourth Proportional to 91.76, 138.19 and 79.88

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Solution

The fourth proportional to 91.76, 138.19 and 79.88 is: 120.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.76 : 138.19 = 79.88 : x
  2. Step 2: Convert to fraction form
    91.76/138.19 = 79.88/x
  3. Step 3: Cross multiply
    91.76x = 138.19 × 79.88
  4. Step 4: Simplify right side
    91.76x = 11,038.22
  5. Step 5: Solve for x
    x = 11,038.22/91.76
  6. Step 6: Final answer
    x = 120.29

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.