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Finding the Fourth Proportional to 78.23, 117.34 and 20.45

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Solution

The fourth proportional to 78.23, 117.34 and 20.45 is: 30.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.23 : 117.34 = 20.45 : x
  2. Step 2: Convert to fraction form
    78.23/117.34 = 20.45/x
  3. Step 3: Cross multiply
    78.23x = 117.34 × 20.45
  4. Step 4: Simplify right side
    78.23x = 2,399.85
  5. Step 5: Solve for x
    x = 2,399.85/78.23
  6. Step 6: Final answer
    x = 30.68

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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.