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Finding the Fourth Proportional to 72, 99 and 68.40

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Solution

The fourth proportional to 72, 99 and 68.40 is: 94.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    72 : 99 = 68.40 : x
  2. Step 2: Convert to fraction form
    72/99 = 68.40/x
  3. Step 3: Cross multiply
    72x = 99 × 68.40
  4. Step 4: Simplify right side
    72x = 6,771.60
  5. Step 5: Solve for x
    x = 6,771.60/72
  6. Step 6: Final answer
    x = 94.05

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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.