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Finding the Fourth Proportional to 13.15, 19.72 and 7.84

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Solution

The fourth proportional to 13.15, 19.72 and 7.84 is: 11.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.15 : 19.72 = 7.84 : x
  2. Step 2: Convert to fraction form
    13.15/19.72 = 7.84/x
  3. Step 3: Cross multiply
    13.15x = 19.72 × 7.84
  4. Step 4: Simplify right side
    13.15x = 154.51
  5. Step 5: Solve for x
    x = 154.51/13.15
  6. Step 6: Final answer
    x = 11.75

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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.