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Finding the Fourth Proportional to 30.58, 42.15 and 21.31

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Solution

The fourth proportional to 30.58, 42.15 and 21.31 is: 29.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.58 : 42.15 = 21.31 : x
  2. Step 2: Convert to fraction form
    30.58/42.15 = 21.31/x
  3. Step 3: Cross multiply
    30.58x = 42.15 × 21.31
  4. Step 4: Simplify right side
    30.58x = 898.25
  5. Step 5: Solve for x
    x = 898.25/30.58
  6. Step 6: Final answer
    x = 29.38

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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.