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Finding the Fourth Proportional to 30.98, 42.74 and 21.28

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Solution

The fourth proportional to 30.98, 42.74 and 21.28 is: 29.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.98 : 42.74 = 21.28 : x
  2. Step 2: Convert to fraction form
    30.98/42.74 = 21.28/x
  3. Step 3: Cross multiply
    30.98x = 42.74 × 21.28
  4. Step 4: Simplify right side
    30.98x = 909.51
  5. Step 5: Solve for x
    x = 909.51/30.98
  6. Step 6: Final answer
    x = 29.36

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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.