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Finding the Fourth Proportional to 20.90, 28.80 and 19.35

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Solution

The fourth proportional to 20.90, 28.80 and 19.35 is: 26.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.90 : 28.80 = 19.35 : x
  2. Step 2: Convert to fraction form
    20.90/28.80 = 19.35/x
  3. Step 3: Cross multiply
    20.90x = 28.80 × 19.35
  4. Step 4: Simplify right side
    20.90x = 557.28
  5. Step 5: Solve for x
    x = 557.28/20.90
  6. Step 6: Final answer
    x = 26.67

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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.