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Finding the Fourth Proportional to 86.95, 120.09 and 64.90

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Solution

The fourth proportional to 86.95, 120.09 and 64.90 is: 89.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.95 : 120.09 = 64.90 : x
  2. Step 2: Convert to fraction form
    86.95/120.09 = 64.90/x
  3. Step 3: Cross multiply
    86.95x = 120.09 × 64.90
  4. Step 4: Simplify right side
    86.95x = 7,793.84
  5. Step 5: Solve for x
    x = 7,793.84/86.95
  6. Step 6: Final answer
    x = 89.64

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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.