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Finding the Fourth Proportional to 91.80, 137.68 and 51.20

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Solution

The fourth proportional to 91.80, 137.68 and 51.20 is: 76.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.80 : 137.68 = 51.20 : x
  2. Step 2: Convert to fraction form
    91.80/137.68 = 51.20/x
  3. Step 3: Cross multiply
    91.80x = 137.68 × 51.20
  4. Step 4: Simplify right side
    91.80x = 7,048.27
  5. Step 5: Solve for x
    x = 7,048.27/91.80
  6. Step 6: Final answer
    x = 76.78

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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.