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Finding the Fourth Proportional to 65.45, 98.12 and 39.78

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Solution

The fourth proportional to 65.45, 98.12 and 39.78 is: 59.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.45 : 98.12 = 39.78 : x
  2. Step 2: Convert to fraction form
    65.45/98.12 = 39.78/x
  3. Step 3: Cross multiply
    65.45x = 98.12 × 39.78
  4. Step 4: Simplify right side
    65.45x = 3,903.31
  5. Step 5: Solve for x
    x = 3,903.31/65.45
  6. Step 6: Final answer
    x = 59.64

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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.