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Finding the Fourth Proportional to 91.89, 138.02 and 57.74

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Solution

The fourth proportional to 91.89, 138.02 and 57.74 is: 86.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.89 : 138.02 = 57.74 : x
  2. Step 2: Convert to fraction form
    91.89/138.02 = 57.74/x
  3. Step 3: Cross multiply
    91.89x = 138.02 × 57.74
  4. Step 4: Simplify right side
    91.89x = 7,968.30
  5. Step 5: Solve for x
    x = 7,968.30/91.89
  6. Step 6: Final answer
    x = 86.72

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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.