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Finding the Fourth Proportional to 78.99, 108.81 and 69.81

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Solution

The fourth proportional to 78.99, 108.81 and 69.81 is: 96.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.99 : 108.81 = 69.81 : x
  2. Step 2: Convert to fraction form
    78.99/108.81 = 69.81/x
  3. Step 3: Cross multiply
    78.99x = 108.81 × 69.81
  4. Step 4: Simplify right side
    78.99x = 7,596.03
  5. Step 5: Solve for x
    x = 7,596.03/78.99
  6. Step 6: Final answer
    x = 96.16

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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.