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Finding the Fourth Proportional to 78.98, 108.70 and 61.42

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Solution

The fourth proportional to 78.98, 108.70 and 61.42 is: 84.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.98 : 108.70 = 61.42 : x
  2. Step 2: Convert to fraction form
    78.98/108.70 = 61.42/x
  3. Step 3: Cross multiply
    78.98x = 108.70 × 61.42
  4. Step 4: Simplify right side
    78.98x = 6,675.93
  5. Step 5: Solve for x
    x = 6,675.93/78.98
  6. Step 6: Final answer
    x = 84.53

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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.