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Finding the Fourth Proportional to 30.78, 42.44 and 21.08

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Solution

The fourth proportional to 30.78, 42.44 and 21.08 is: 29.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.78 : 42.44 = 21.08 : x
  2. Step 2: Convert to fraction form
    30.78/42.44 = 21.08/x
  3. Step 3: Cross multiply
    30.78x = 42.44 × 21.08
  4. Step 4: Simplify right side
    30.78x = 894.32
  5. Step 5: Solve for x
    x = 894.32/30.78
  6. Step 6: Final answer
    x = 29.06

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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.