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Finding the Fourth Proportional to 31.16, 43.00 and 21.20

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Solution

The fourth proportional to 31.16, 43.00 and 21.20 is: 29.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.16 : 43.00 = 21.20 : x
  2. Step 2: Convert to fraction form
    31.16/43.00 = 21.20/x
  3. Step 3: Cross multiply
    31.16x = 43.00 × 21.20
  4. Step 4: Simplify right side
    31.16x = 911.48
  5. Step 5: Solve for x
    x = 911.48/31.16
  6. Step 6: Final answer
    x = 29.25

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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.