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Finding the Fourth Proportional to 84.90, 126.80 and 66.81

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Solution

The fourth proportional to 84.90, 126.80 and 66.81 is: 99.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.90 : 126.80 = 66.81 : x
  2. Step 2: Convert to fraction form
    84.90/126.80 = 66.81/x
  3. Step 3: Cross multiply
    84.90x = 126.80 × 66.81
  4. Step 4: Simplify right side
    84.90x = 8,471.51
  5. Step 5: Solve for x
    x = 8,471.51/84.90
  6. Step 6: Final answer
    x = 99.78

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.