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Finding the Fourth Proportional to 83.86, 126.40 and 78.28

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Solution

The fourth proportional to 83.86, 126.40 and 78.28 is: 117.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.86 : 126.40 = 78.28 : x
  2. Step 2: Convert to fraction form
    83.86/126.40 = 78.28/x
  3. Step 3: Cross multiply
    83.86x = 126.40 × 78.28
  4. Step 4: Simplify right side
    83.86x = 9,894.59
  5. Step 5: Solve for x
    x = 9,894.59/83.86
  6. Step 6: Final answer
    x = 117.99

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.