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Finding the Fourth Proportional to 76.79, 115 and 42.47

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Solution

The fourth proportional to 76.79, 115 and 42.47 is: 63.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.79 : 115 = 42.47 : x
  2. Step 2: Convert to fraction form
    76.79/115 = 42.47/x
  3. Step 3: Cross multiply
    76.79x = 115 × 42.47
  4. Step 4: Simplify right side
    76.79x = 4,884.05
  5. Step 5: Solve for x
    x = 4,884.05/76.79
  6. Step 6: Final answer
    x = 63.60

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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.