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Finding the Fourth Proportional to 30.58, 42.20 and 21.36

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Solution

The fourth proportional to 30.58, 42.20 and 21.36 is: 29.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.58 : 42.20 = 21.36 : x
  2. Step 2: Convert to fraction form
    30.58/42.20 = 21.36/x
  3. Step 3: Cross multiply
    30.58x = 42.20 × 21.36
  4. Step 4: Simplify right side
    30.58x = 901.39
  5. Step 5: Solve for x
    x = 901.39/30.58
  6. Step 6: Final answer
    x = 29.48

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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.