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Finding the Fourth Proportional to 51.45, 77.11 and 21

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Solution

The fourth proportional to 51.45, 77.11 and 21 is: 31.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.45 : 77.11 = 21 : x
  2. Step 2: Convert to fraction form
    51.45/77.11 = 21/x
  3. Step 3: Cross multiply
    51.45x = 77.11 × 21
  4. Step 4: Simplify right side
    51.45x = 1,619.31
  5. Step 5: Solve for x
    x = 1,619.31/51.45
  6. Step 6: Final answer
    x = 31.47

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.