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Finding the Fourth Proportional to 25.80, 38.64 and 20.40

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Solution

The fourth proportional to 25.80, 38.64 and 20.40 is: 30.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    25.80 : 38.64 = 20.40 : x
  2. Step 2: Convert to fraction form
    25.80/38.64 = 20.40/x
  3. Step 3: Cross multiply
    25.80x = 38.64 × 20.40
  4. Step 4: Simplify right side
    25.80x = 788.26
  5. Step 5: Solve for x
    x = 788.26/25.80
  6. Step 6: Final answer
    x = 30.55

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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.