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Finding the Fourth Proportional to 126.84, 189.84 and 78.78

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Solution

The fourth proportional to 126.84, 189.84 and 78.78 is: 117.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.84 : 189.84 = 78.78 : x
  2. Step 2: Convert to fraction form
    126.84/189.84 = 78.78/x
  3. Step 3: Cross multiply
    126.84x = 189.84 × 78.78
  4. Step 4: Simplify right side
    126.84x = 14,955.60
  5. Step 5: Solve for x
    x = 14,955.60/126.84
  6. Step 6: Final answer
    x = 117.91

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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.