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Finding the Fourth Proportional to 126.66, 189.90 and 78.60

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Solution

The fourth proportional to 126.66, 189.90 and 78.60 is: 117.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.66 : 189.90 = 78.60 : x
  2. Step 2: Convert to fraction form
    126.66/189.90 = 78.60/x
  3. Step 3: Cross multiply
    126.66x = 189.90 × 78.60
  4. Step 4: Simplify right side
    126.66x = 14,926.14
  5. Step 5: Solve for x
    x = 14,926.14/126.66
  6. Step 6: Final answer
    x = 117.84

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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.