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Finding the Fourth Proportional to 30.84, 42.51 and 21.12

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Solution

The fourth proportional to 30.84, 42.51 and 21.12 is: 29.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.84 : 42.51 = 21.12 : x
  2. Step 2: Convert to fraction form
    30.84/42.51 = 21.12/x
  3. Step 3: Cross multiply
    30.84x = 42.51 × 21.12
  4. Step 4: Simplify right side
    30.84x = 897.81
  5. Step 5: Solve for x
    x = 897.81/30.84
  6. Step 6: Final answer
    x = 29.11

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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.