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Finding the Fourth Proportional to 114.72, 172.21 and 78.39

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Solution

The fourth proportional to 114.72, 172.21 and 78.39 is: 117.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    114.72 : 172.21 = 78.39 : x
  2. Step 2: Convert to fraction form
    114.72/172.21 = 78.39/x
  3. Step 3: Cross multiply
    114.72x = 172.21 × 78.39
  4. Step 4: Simplify right side
    114.72x = 13,499.54
  5. Step 5: Solve for x
    x = 13,499.54/114.72
  6. Step 6: Final answer
    x = 117.67

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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.