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Finding the Fourth Proportional to 21.90, 31.08 and 21.90

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Solution

The fourth proportional to 21.90, 31.08 and 21.90 is: 31.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.90 : 31.08 = 21.90 : x
  2. Step 2: Convert to fraction form
    21.90/31.08 = 21.90/x
  3. Step 3: Cross multiply
    21.90x = 31.08 × 21.90
  4. Step 4: Simplify right side
    21.90x = 680.65
  5. Step 5: Solve for x
    x = 680.65/21.90
  6. Step 6: Final answer
    x = 31.08

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Why These Related Problems?

These problems maintain the same ratio (1.42) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.