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Finding the Fourth Proportional to 19.40, 26.78 and 15.78

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Solution

The fourth proportional to 19.40, 26.78 and 15.78 is: 21.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.40 : 26.78 = 15.78 : x
  2. Step 2: Convert to fraction form
    19.40/26.78 = 15.78/x
  3. Step 3: Cross multiply
    19.40x = 26.78 × 15.78
  4. Step 4: Simplify right side
    19.40x = 422.59
  5. Step 5: Solve for x
    x = 422.59/19.40
  6. Step 6: Final answer
    x = 21.78

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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.