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Finding the Fourth Proportional to 19.70, 27.18 and 12.78

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Solution

The fourth proportional to 19.70, 27.18 and 12.78 is: 17.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.70 : 27.18 = 12.78 : x
  2. Step 2: Convert to fraction form
    19.70/27.18 = 12.78/x
  3. Step 3: Cross multiply
    19.70x = 27.18 × 12.78
  4. Step 4: Simplify right side
    19.70x = 347.36
  5. Step 5: Solve for x
    x = 347.36/19.70
  6. Step 6: Final answer
    x = 17.64

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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.