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Finding the Fourth Proportional to 91.85, 136.99 and 78.23

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Solution

The fourth proportional to 91.85, 136.99 and 78.23 is: 116.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.85 : 136.99 = 78.23 : x
  2. Step 2: Convert to fraction form
    91.85/136.99 = 78.23/x
  3. Step 3: Cross multiply
    91.85x = 136.99 × 78.23
  4. Step 4: Simplify right side
    91.85x = 10,715.99
  5. Step 5: Solve for x
    x = 10,715.99/91.85
  6. Step 6: Final answer
    x = 116.67

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.