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Finding the Fourth Proportional to 66.80, 100.20 and 66.40

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Solution

The fourth proportional to 66.80, 100.20 and 66.40 is: 99.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.80 : 100.20 = 66.40 : x
  2. Step 2: Convert to fraction form
    66.80/100.20 = 66.40/x
  3. Step 3: Cross multiply
    66.80x = 100.20 × 66.40
  4. Step 4: Simplify right side
    66.80x = 6,653.28
  5. Step 5: Solve for x
    x = 6,653.28/66.80
  6. Step 6: Final answer
    x = 99.60

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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.