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Finding the Fourth Proportional to 118.61, 177.91 and 78.31

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Solution

The fourth proportional to 118.61, 177.91 and 78.31 is: 117.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    118.61 : 177.91 = 78.31 : x
  2. Step 2: Convert to fraction form
    118.61/177.91 = 78.31/x
  3. Step 3: Cross multiply
    118.61x = 177.91 × 78.31
  4. Step 4: Simplify right side
    118.61x = 13,931.49
  5. Step 5: Solve for x
    x = 13,931.49/118.61
  6. Step 6: Final answer
    x = 117.46

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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.