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Finding the Fourth Proportional to 91.95, 138.15 and 57.78

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Solution

The fourth proportional to 91.95, 138.15 and 57.78 is: 86.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.95 : 138.15 = 57.78 : x
  2. Step 2: Convert to fraction form
    91.95/138.15 = 57.78/x
  3. Step 3: Cross multiply
    91.95x = 138.15 × 57.78
  4. Step 4: Simplify right side
    91.95x = 7,981.33
  5. Step 5: Solve for x
    x = 7,981.33/91.95
  6. Step 6: Final answer
    x = 86.81

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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.