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Finding the Fourth Proportional to 111.68, 153.99 and 78.51

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Solution

The fourth proportional to 111.68, 153.99 and 78.51 is: 108.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.68 : 153.99 = 78.51 : x
  2. Step 2: Convert to fraction form
    111.68/153.99 = 78.51/x
  3. Step 3: Cross multiply
    111.68x = 153.99 × 78.51
  4. Step 4: Simplify right side
    111.68x = 12,089.75
  5. Step 5: Solve for x
    x = 12,089.75/111.68
  6. Step 6: Final answer
    x = 108.25

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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.