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Finding the Fourth Proportional to 30.97, 42.74 and 21.79

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Solution

The fourth proportional to 30.97, 42.74 and 21.79 is: 30.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.97 : 42.74 = 21.79 : x
  2. Step 2: Convert to fraction form
    30.97/42.74 = 21.79/x
  3. Step 3: Cross multiply
    30.97x = 42.74 × 21.79
  4. Step 4: Simplify right side
    30.97x = 931.21
  5. Step 5: Solve for x
    x = 931.21/30.97
  6. Step 6: Final answer
    x = 30.07

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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.