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Finding the Fourth Proportional to 66.75, 99.90 and 39.57

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Solution

The fourth proportional to 66.75, 99.90 and 39.57 is: 59.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.75 : 99.90 = 39.57 : x
  2. Step 2: Convert to fraction form
    66.75/99.90 = 39.57/x
  3. Step 3: Cross multiply
    66.75x = 99.90 × 39.57
  4. Step 4: Simplify right side
    66.75x = 3,953.04
  5. Step 5: Solve for x
    x = 3,953.04/66.75
  6. Step 6: Final answer
    x = 59.22

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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.