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Finding the Fourth Proportional to 78.29, 117.42 and 20.51

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Solution

The fourth proportional to 78.29, 117.42 and 20.51 is: 30.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.29 : 117.42 = 20.51 : x
  2. Step 2: Convert to fraction form
    78.29/117.42 = 20.51/x
  3. Step 3: Cross multiply
    78.29x = 117.42 × 20.51
  4. Step 4: Simplify right side
    78.29x = 2,407.70
  5. Step 5: Solve for x
    x = 2,407.70/78.29
  6. Step 6: Final answer
    x = 30.76

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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.