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Finding the Fourth Proportional to 45, 67.56 and 30.78

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Solution

The fourth proportional to 45, 67.56 and 30.78 is: 46.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    45 : 67.56 = 30.78 : x
  2. Step 2: Convert to fraction form
    45/67.56 = 30.78/x
  3. Step 3: Cross multiply
    45x = 67.56 × 30.78
  4. Step 4: Simplify right side
    45x = 2,079.50
  5. Step 5: Solve for x
    x = 2,079.50/45
  6. Step 6: Final answer
    x = 46.21

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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.