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Finding the Fourth Proportional to 91.97, 137.28 and 78.30

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Solution

The fourth proportional to 91.97, 137.28 and 78.30 is: 116.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.97 : 137.28 = 78.30 : x
  2. Step 2: Convert to fraction form
    91.97/137.28 = 78.30/x
  3. Step 3: Cross multiply
    91.97x = 137.28 × 78.30
  4. Step 4: Simplify right side
    91.97x = 10,749.02
  5. Step 5: Solve for x
    x = 10,749.02/91.97
  6. Step 6: Final answer
    x = 116.88

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.