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Finding the Fourth Proportional to 66.90, 100.35 and 21.24

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Solution

The fourth proportional to 66.90, 100.35 and 21.24 is: 31.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.90 : 100.35 = 21.24 : x
  2. Step 2: Convert to fraction form
    66.90/100.35 = 21.24/x
  3. Step 3: Cross multiply
    66.90x = 100.35 × 21.24
  4. Step 4: Simplify right side
    66.90x = 2,131.33
  5. Step 5: Solve for x
    x = 2,131.33/66.90
  6. Step 6: Final answer
    x = 31.86

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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.