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Finding the Fourth Proportional to 126.80, 189.88 and 78.56

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Solution

The fourth proportional to 126.80, 189.88 and 78.56 is: 117.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.80 : 189.88 = 78.56 : x
  2. Step 2: Convert to fraction form
    126.80/189.88 = 78.56/x
  3. Step 3: Cross multiply
    126.80x = 189.88 × 78.56
  4. Step 4: Simplify right side
    126.80x = 14,916.97
  5. Step 5: Solve for x
    x = 14,916.97/126.80
  6. Step 6: Final answer
    x = 117.64

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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.