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Finding the Fourth Proportional to 260.40, 390.64 and 77.76

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Solution

The fourth proportional to 260.40, 390.64 and 77.76 is: 116.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    260.40 : 390.64 = 77.76 : x
  2. Step 2: Convert to fraction form
    260.40/390.64 = 77.76/x
  3. Step 3: Cross multiply
    260.40x = 390.64 × 77.76
  4. Step 4: Simplify right side
    260.40x = 30,376.17
  5. Step 5: Solve for x
    x = 30,376.17/260.40
  6. Step 6: Final answer
    x = 116.65

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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.