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Finding the Fourth Proportional to 78.45, 117.67 and 20.67

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Solution

The fourth proportional to 78.45, 117.67 and 20.67 is: 31.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.45 : 117.67 = 20.67 : x
  2. Step 2: Convert to fraction form
    78.45/117.67 = 20.67/x
  3. Step 3: Cross multiply
    78.45x = 117.67 × 20.67
  4. Step 4: Simplify right side
    78.45x = 2,432.24
  5. Step 5: Solve for x
    x = 2,432.24/78.45
  6. Step 6: Final answer
    x = 31.00

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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.