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Finding the Fourth Proportional to 76.68, 115 and 31

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Solution

The fourth proportional to 76.68, 115 and 31 is: 46.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.68 : 115 = 31 : x
  2. Step 2: Convert to fraction form
    76.68/115 = 31/x
  3. Step 3: Cross multiply
    76.68x = 115 × 31
  4. Step 4: Simplify right side
    76.68x = 3,565
  5. Step 5: Solve for x
    x = 3,565/76.68
  6. Step 6: Final answer
    x = 46.49

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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.