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Finding the Fourth Proportional to 118.99, 178.21 and 78.42

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Solution

The fourth proportional to 118.99, 178.21 and 78.42 is: 117.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    118.99 : 178.21 = 78.42 : x
  2. Step 2: Convert to fraction form
    118.99/178.21 = 78.42/x
  3. Step 3: Cross multiply
    118.99x = 178.21 × 78.42
  4. Step 4: Simplify right side
    118.99x = 13,975.23
  5. Step 5: Solve for x
    x = 13,975.23/118.99
  6. Step 6: Final answer
    x = 117.45

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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.