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Finding the Fourth Proportional to 260.49, 390.81 and 77.90

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Solution

The fourth proportional to 260.49, 390.81 and 77.90 is: 116.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.49 : 390.81 = 77.90 : x
  2. Step 2: Convert to fraction form
    260.49/390.81 = 77.90/x
  3. Step 3: Cross multiply
    260.49x = 390.81 × 77.90
  4. Step 4: Simplify right side
    260.49x = 30,442.14
  5. Step 5: Solve for x
    x = 30,442.14/260.49
  6. Step 6: Final answer
    x = 116.86

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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.