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Finding the Fourth Proportional to 91.28, 125.91 and 56.78

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Solution

The fourth proportional to 91.28, 125.91 and 56.78 is: 78.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.28 : 125.91 = 56.78 : x
  2. Step 2: Convert to fraction form
    91.28/125.91 = 56.78/x
  3. Step 3: Cross multiply
    91.28x = 125.91 × 56.78
  4. Step 4: Simplify right side
    91.28x = 7,149.17
  5. Step 5: Solve for x
    x = 7,149.17/91.28
  6. Step 6: Final answer
    x = 78.32

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.