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Finding the Fourth Proportional to 172.69, 258.91 and 86.00

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Solution

The fourth proportional to 172.69, 258.91 and 86.00 is: 128.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.69 : 258.91 = 86.00 : x
  2. Step 2: Convert to fraction form
    172.69/258.91 = 86.00/x
  3. Step 3: Cross multiply
    172.69x = 258.91 × 86.00
  4. Step 4: Simplify right side
    172.69x = 22,264.75
  5. Step 5: Solve for x
    x = 22,264.75/172.69
  6. Step 6: Final answer
    x = 128.93

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.