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Finding the Fourth Proportional to 76.64, 105.78 and 47.56

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Solution

The fourth proportional to 76.64, 105.78 and 47.56 is: 65.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.64 : 105.78 = 47.56 : x
  2. Step 2: Convert to fraction form
    76.64/105.78 = 47.56/x
  3. Step 3: Cross multiply
    76.64x = 105.78 × 47.56
  4. Step 4: Simplify right side
    76.64x = 5,030.90
  5. Step 5: Solve for x
    x = 5,030.90/76.64
  6. Step 6: Final answer
    x = 65.64

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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.