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Finding the Fourth Proportional to 76.60, 105.70 and 42.10

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Solution

The fourth proportional to 76.60, 105.70 and 42.10 is: 58.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.60 : 105.70 = 42.10 : x
  2. Step 2: Convert to fraction form
    76.60/105.70 = 42.10/x
  3. Step 3: Cross multiply
    76.60x = 105.70 × 42.10
  4. Step 4: Simplify right side
    76.60x = 4,449.97
  5. Step 5: Solve for x
    x = 4,449.97/76.60
  6. Step 6: Final answer
    x = 58.09

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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.