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Finding the Fourth Proportional to 66.40, 91.63 and 38.78

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Solution

The fourth proportional to 66.40, 91.63 and 38.78 is: 53.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.40 : 91.63 = 38.78 : x
  2. Step 2: Convert to fraction form
    66.40/91.63 = 38.78/x
  3. Step 3: Cross multiply
    66.40x = 91.63 × 38.78
  4. Step 4: Simplify right side
    66.40x = 3,553.41
  5. Step 5: Solve for x
    x = 3,553.41/66.40
  6. Step 6: Final answer
    x = 53.52

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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.