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Finding the Fourth Proportional to 66.42, 91.64 and 38.79

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Solution

The fourth proportional to 66.42, 91.64 and 38.79 is: 53.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.42 : 91.64 = 38.79 : x
  2. Step 2: Convert to fraction form
    66.42/91.64 = 38.79/x
  3. Step 3: Cross multiply
    66.42x = 91.64 × 38.79
  4. Step 4: Simplify right side
    66.42x = 3,554.72
  5. Step 5: Solve for x
    x = 3,554.72/66.42
  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.