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Finding the Fourth Proportional to 78.28, 116.90 and 77.43

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Solution

The fourth proportional to 78.28, 116.90 and 77.43 is: 115.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.28 : 116.90 = 77.43 : x
  2. Step 2: Convert to fraction form
    78.28/116.90 = 77.43/x
  3. Step 3: Cross multiply
    78.28x = 116.90 × 77.43
  4. Step 4: Simplify right side
    78.28x = 9,051.86
  5. Step 5: Solve for x
    x = 9,051.86/78.28
  6. Step 6: Final answer
    x = 115.63

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.