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Finding the Fourth Proportional to 85.70, 117.40 and 78.41

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Solution

The fourth proportional to 85.70, 117.40 and 78.41 is: 107.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.70 : 117.40 = 78.41 : x
  2. Step 2: Convert to fraction form
    85.70/117.40 = 78.41/x
  3. Step 3: Cross multiply
    85.70x = 117.40 × 78.41
  4. Step 4: Simplify right side
    85.70x = 9,205.33
  5. Step 5: Solve for x
    x = 9,205.33/85.70
  6. Step 6: Final answer
    x = 107.41

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.