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Finding the Fourth Proportional to 78.28, 117.57 and 72.81

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Solution

The fourth proportional to 78.28, 117.57 and 72.81 is: 109.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.28 : 117.57 = 72.81 : x
  2. Step 2: Convert to fraction form
    78.28/117.57 = 72.81/x
  3. Step 3: Cross multiply
    78.28x = 117.57 × 72.81
  4. Step 4: Simplify right side
    78.28x = 8,559.91
  5. Step 5: Solve for x
    x = 8,559.91/78.28
  6. Step 6: Final answer
    x = 109.36

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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.