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Finding the Fourth Proportional to 31.08, 42.94 and 21.40

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Solution

The fourth proportional to 31.08, 42.94 and 21.40 is: 29.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.08 : 42.94 = 21.40 : x
  2. Step 2: Convert to fraction form
    31.08/42.94 = 21.40/x
  3. Step 3: Cross multiply
    31.08x = 42.94 × 21.40
  4. Step 4: Simplify right side
    31.08x = 918.92
  5. Step 5: Solve for x
    x = 918.92/31.08
  6. Step 6: Final answer
    x = 29.57

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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.