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Finding the Fourth Proportional to 78.38, 107.99 and 72.71

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Solution

The fourth proportional to 78.38, 107.99 and 72.71 is: 100.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.38 : 107.99 = 72.71 : x
  2. Step 2: Convert to fraction form
    78.38/107.99 = 72.71/x
  3. Step 3: Cross multiply
    78.38x = 107.99 × 72.71
  4. Step 4: Simplify right side
    78.38x = 7,851.95
  5. Step 5: Solve for x
    x = 7,851.95/78.38
  6. Step 6: Final answer
    x = 100.18

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.