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Finding the Fourth Proportional to 91.15, 125.78 and 51.80

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Solution

The fourth proportional to 91.15, 125.78 and 51.80 is: 71.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.15 : 125.78 = 51.80 : x
  2. Step 2: Convert to fraction form
    91.15/125.78 = 51.80/x
  3. Step 3: Cross multiply
    91.15x = 125.78 × 51.80
  4. Step 4: Simplify right side
    91.15x = 6,515.59
  5. Step 5: Solve for x
    x = 6,515.59/91.15
  6. Step 6: Final answer
    x = 71.48

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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.