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Finding the Fourth Proportional to 102.99, 142 and 78.39

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Solution

The fourth proportional to 102.99, 142 and 78.39 is: 108.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.99 : 142 = 78.39 : x
  2. Step 2: Convert to fraction form
    102.99/142 = 78.39/x
  3. Step 3: Cross multiply
    102.99x = 142 × 78.39
  4. Step 4: Simplify right side
    102.99x = 11,131.38
  5. Step 5: Solve for x
    x = 11,131.38/102.99
  6. Step 6: Final answer
    x = 108.08

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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.