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Finding the Fourth Proportional to 72, 98.70 and 70.85

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Solution

The fourth proportional to 72, 98.70 and 70.85 is: 97.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    72 : 98.70 = 70.85 : x
  2. Step 2: Convert to fraction form
    72/98.70 = 70.85/x
  3. Step 3: Cross multiply
    72x = 98.70 × 70.85
  4. Step 4: Simplify right side
    72x = 6,992.88
  5. Step 5: Solve for x
    x = 6,992.88/72
  6. Step 6: Final answer
    x = 97.12

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.