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Finding the Fourth Proportional to 31.05, 42.84 and 21.35

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Solution

The fourth proportional to 31.05, 42.84 and 21.35 is: 29.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.05 : 42.84 = 21.35 : x
  2. Step 2: Convert to fraction form
    31.05/42.84 = 21.35/x
  3. Step 3: Cross multiply
    31.05x = 42.84 × 21.35
  4. Step 4: Simplify right side
    31.05x = 914.42
  5. Step 5: Solve for x
    x = 914.42/31.05
  6. Step 6: Final answer
    x = 29.45

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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.