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Finding the Fourth Proportional to 70.40, 105.39 and 61.40

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Solution

The fourth proportional to 70.40, 105.39 and 61.40 is: 91.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.40 : 105.39 = 61.40 : x
  2. Step 2: Convert to fraction form
    70.40/105.39 = 61.40/x
  3. Step 3: Cross multiply
    70.40x = 105.39 × 61.40
  4. Step 4: Simplify right side
    70.40x = 6,471.21
  5. Step 5: Solve for x
    x = 6,471.21/70.40
  6. Step 6: Final answer
    x = 91.92

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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.