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Finding the Fourth Proportional to 76.71, 105.85 and 42.21

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Solution

The fourth proportional to 76.71, 105.85 and 42.21 is: 58.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.71 : 105.85 = 42.21 : x
  2. Step 2: Convert to fraction form
    76.71/105.85 = 42.21/x
  3. Step 3: Cross multiply
    76.71x = 105.85 × 42.21
  4. Step 4: Simplify right side
    76.71x = 4,467.40
  5. Step 5: Solve for x
    x = 4,467.40/76.71
  6. Step 6: Final answer
    x = 58.24

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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.