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Finding the Fourth Proportional to 5.20, 7.80 and 2.66

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Solution

The fourth proportional to 5.20, 7.80 and 2.66 is: 4.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    5.20 : 7.80 = 2.66 : x
  2. Step 2: Convert to fraction form
    5.20/7.80 = 2.66/x
  3. Step 3: Cross multiply
    5.20x = 7.80 × 2.66
  4. Step 4: Simplify right side
    5.20x = 20.77
  5. Step 5: Solve for x
    x = 20.77/5.20
  6. Step 6: Final answer
    x = 4.00

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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.