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Finding the Fourth Proportional to 78.99, 109.20 and 75.78

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Solution

The fourth proportional to 78.99, 109.20 and 75.78 is: 104.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.99 : 109.20 = 75.78 : x
  2. Step 2: Convert to fraction form
    78.99/109.20 = 75.78/x
  3. Step 3: Cross multiply
    78.99x = 109.20 × 75.78
  4. Step 4: Simplify right side
    78.99x = 8,275.18
  5. Step 5: Solve for x
    x = 8,275.18/78.99
  6. Step 6: Final answer
    x = 104.76

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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.