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Finding the Fourth Proportional to 111.47, 153.89 and 78.75

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Solution

The fourth proportional to 111.47, 153.89 and 78.75 is: 108.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.47 : 153.89 = 78.75 : x
  2. Step 2: Convert to fraction form
    111.47/153.89 = 78.75/x
  3. Step 3: Cross multiply
    111.47x = 153.89 × 78.75
  4. Step 4: Simplify right side
    111.47x = 12,118.44
  5. Step 5: Solve for x
    x = 12,118.44/111.47
  6. Step 6: Final answer
    x = 108.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.