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Finding the Fourth Proportional to 78.42, 117.40 and 74.12

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Solution

The fourth proportional to 78.42, 117.40 and 74.12 is: 110.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.42 : 117.40 = 74.12 : x
  2. Step 2: Convert to fraction form
    78.42/117.40 = 74.12/x
  3. Step 3: Cross multiply
    78.42x = 117.40 × 74.12
  4. Step 4: Simplify right side
    78.42x = 8,701.05
  5. Step 5: Solve for x
    x = 8,701.05/78.42
  6. Step 6: Final answer
    x = 110.96

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.