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Finding the Fourth Proportional to 77.09, 115.66 and 31.45

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Solution

The fourth proportional to 77.09, 115.66 and 31.45 is: 47.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.09 : 115.66 = 31.45 : x
  2. Step 2: Convert to fraction form
    77.09/115.66 = 31.45/x
  3. Step 3: Cross multiply
    77.09x = 115.66 × 31.45
  4. Step 4: Simplify right side
    77.09x = 3,636.93
  5. Step 5: Solve for x
    x = 3,636.93/77.09
  6. Step 6: Final answer
    x = 47.18

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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.