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Finding the Fourth Proportional to 76.30, 105.21 and 61.57

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Solution

The fourth proportional to 76.30, 105.21 and 61.57 is: 84.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.30 : 105.21 = 61.57 : x
  2. Step 2: Convert to fraction form
    76.30/105.21 = 61.57/x
  3. Step 3: Cross multiply
    76.30x = 105.21 × 61.57
  4. Step 4: Simplify right side
    76.30x = 6,477.78
  5. Step 5: Solve for x
    x = 6,477.78/76.30
  6. Step 6: Final answer
    x = 84.90

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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.