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Finding the Fourth Proportional to 9.80, 13.55 and 7.87

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Solution

The fourth proportional to 9.80, 13.55 and 7.87 is: 10.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    9.80 : 13.55 = 7.87 : x
  2. Step 2: Convert to fraction form
    9.80/13.55 = 7.87/x
  3. Step 3: Cross multiply
    9.80x = 13.55 × 7.87
  4. Step 4: Simplify right side
    9.80x = 106.64
  5. Step 5: Solve for x
    x = 106.64/9.80
  6. Step 6: Final answer
    x = 10.88

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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.