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Finding the Fourth Proportional to 42.42, 63.61 and 21.05

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Solution

The fourth proportional to 42.42, 63.61 and 21.05 is: 31.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.42 : 63.61 = 21.05 : x
  2. Step 2: Convert to fraction form
    42.42/63.61 = 21.05/x
  3. Step 3: Cross multiply
    42.42x = 63.61 × 21.05
  4. Step 4: Simplify right side
    42.42x = 1,338.99
  5. Step 5: Solve for x
    x = 1,338.99/42.42
  6. Step 6: Final answer
    x = 31.57

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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.