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Finding the Fourth Proportional to 103.51, 142.78 and 78.91

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Solution

The fourth proportional to 103.51, 142.78 and 78.91 is: 108.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.51 : 142.78 = 78.91 : x
  2. Step 2: Convert to fraction form
    103.51/142.78 = 78.91/x
  3. Step 3: Cross multiply
    103.51x = 142.78 × 78.91
  4. Step 4: Simplify right side
    103.51x = 11,266.22
  5. Step 5: Solve for x
    x = 11,266.22/103.51
  6. Step 6: Final answer
    x = 108.84

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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.