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Finding the Fourth Proportional to 40.55, 60.78 and 21.28

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Solution

The fourth proportional to 40.55, 60.78 and 21.28 is: 31.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    40.55 : 60.78 = 21.28 : x
  2. Step 2: Convert to fraction form
    40.55/60.78 = 21.28/x
  3. Step 3: Cross multiply
    40.55x = 60.78 × 21.28
  4. Step 4: Simplify right side
    40.55x = 1,293.40
  5. Step 5: Solve for x
    x = 1,293.40/40.55
  6. Step 6: Final answer
    x = 31.90

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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.