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Finding the Fourth Proportional to 91.21, 136.70 and 79.77

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Solution

The fourth proportional to 91.21, 136.70 and 79.77 is: 119.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.21 : 136.70 = 79.77 : x
  2. Step 2: Convert to fraction form
    91.21/136.70 = 79.77/x
  3. Step 3: Cross multiply
    91.21x = 136.70 × 79.77
  4. Step 4: Simplify right side
    91.21x = 10,904.56
  5. Step 5: Solve for x
    x = 10,904.56/91.21
  6. Step 6: Final answer
    x = 119.55

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.