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Finding the Fourth Proportional to 86.18, 128.64 and 70.99

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Solution

The fourth proportional to 86.18, 128.64 and 70.99 is: 105.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.18 : 128.64 = 70.99 : x
  2. Step 2: Convert to fraction form
    86.18/128.64 = 70.99/x
  3. Step 3: Cross multiply
    86.18x = 128.64 × 70.99
  4. Step 4: Simplify right side
    86.18x = 9,132.10
  5. Step 5: Solve for x
    x = 9,132.10/86.18
  6. Step 6: Final answer
    x = 105.97

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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.